for Cold Climate Housing and much more

Last Updated: , Created: Thursday, October 14th, 1999



This is one of those problems that are not dealt with seriously enough by the building officials in really cold regions.  I have opened a blog space at the bottom of this article for you to add in your case history so we can demonstrate that this is a large and continuing problem.  Take a look; not only so you feel less alone, but to see that after years of struggling, my visitors are finding solutions that work for them.  Read all the way down to the bottom of the article (just before the blog) because solutions are appearing and they are getting better and better as time goes on.


Plumbing traps, like the loop you can see under the sink, are designed to stay full of water and block those odours from coming back into the house from the sewage system while letting the plumbing waste through to the sewer system.  At the end of use, water stays behind, keeping the trap full.  They don't always work and you can get annoying to nasty smells in the house when the water does not close the trap.  The good news is that although these odours are very disagreeable, health authorities tell me that this nasty smell is not really a health risk as the gasses are not biologically active (backed up sewage water is dangerous for the health but not the gasses that come off that water) and you would have to be a city maintenance man working in the sewer pipe itself before the concentrations of these gasses would be a real problem.  That probably explains why there is not much plumbing code work done on making sure that plumbing traps work 100% of the time.


The problem

There are two different mechanisms that can dry out these traps and let the smells into the house:

-- Evaporation:  If a drain sitting in a dry atmosphere is not used for a long time, the water simply dries out -- something very common in basement floor drains -- or in houses or individual drains not used for a long time.  That is part of the genius of the system, the more you use it, the more reliable it is.  Sometimes your problem can be solved simply by occasionally pouring a cup of water into otherwise smelly drains.

-- Blockage of the plumbing stack:   All of the water drains in the house are connected to a plumbing vent pipe which goes through the attic and sticks out on the roof. The drainage vent system is shown in the graphic in Red.  This vent piping allows air to flow in the drain system and prevents water flowing down the drain from trying to draw air through the drain traps.  If you didn't have such a vent -- or if it is blocked off -- things would drain very slowly indeed, and probably gurgle in every sink in the house when you drained the bathtub.  If it gurgles enough it will suck the water right out of the trap, letting sewer gasses into the house until you fill the trap the next time you run a little water into it.  This is why all toilets are designed to trickle a little water into the bowl after the flush is completed -- the flush is designed to completely empty the bowl with a syphon action and then the trickle is designed to add fresh water up high enough in the bowl to block the odours in the sewage piping.


The Solutions

Evaporation problems, especially in basement drains can be dealt with in several ways.

-- Pour a little Mineral Oil in the drain to float on the water and slow down the evaporation.  Highly refined Mineral Oil, found in drug stores, can solve the problem.  I had said that it was bio-degradable, but Fred wrote in (see blog below) to point out to me that it is a petroleum product and is not bio-degradable -- and Fred is basically right.  Although some consider the drug store grade highly refined mineral oil to be slowly bio-degradable, its real characteristics that are useful here is that it is without any odour, it will not go rancid, it evaporates extremely slowly and it is really non-toxic. That last point is demonstrated by it being recommended to ingest for constipation -- the reason for which it is stocked in drug stores.  This works for a long time in the drain, but not forever, and it takes a lot of water flow to flush it on down the drain pipe.

-- Run a water line to the drain connected to a special drain filler valve put in the line to the washing machine.  Every time the washing machine kicks off, giving a shock to the plumbing line, the valve squirts a little water into the drain.  This is a great permanent solution, but often requires digging up concrete to get that pipe to the drain.

-- Add a dry valve to the floor trap.  This is a little inexpensive gadget that will let water into the drain but will not let gas out, so it doesn't matter if there is water in the trap or not -- the best known of these is called Dranger.  Follow this link for details on difficult floor traps.


Vent Stack blockage

Although a bird's nest in the spring can cause trouble, the most common source is ice build up at the top of the stack, called Ice Capping, which literally closes the vent pipe with a block of ice.  The ice cap can often be seen from the ground with the zoom on a camera or a pair of binoculars.  The traditional solution is to climb up on the roof and pour boiling water down the pipe -- and then relax the rest of the winter with a broken leg from falling off the roof.  There are two mechanisms that can cause this icing to happen, and they can occasionally work together.

Wet blowing snow with just the right temperature conditions, as is common in Winnipeg, can deposit the ice on the top.

Hot water running down the drain gives off steam, particularly with a hot shower. This steam finds its way up the plumbing vent and out the top of the house. If you have heavily insulated your attic and live in an extremely cold climate, the upper portion of that vent pipe is much colder than it was before you insulated -- and so the steam freezes to the top of the vent pipe before it escapes out the top.


Pipe Sizes

The building code was modified to require that old 1-1/2 inch pipes used for plumbing stacks be increased to 3" when they go out through the roof.  The larger pipe prevents ice from totally closing off the top in many parts of Canada but I am getting more and more reports that even this is not working.

At one point CMHC responded to this "Northern problem", which I am discovering is more prevalent that we think even in areas like northern Ontario, with a great little free publication on the problem.  Unfortunately the Harper years saw CMHC research and publications shut down and the documents dissapeared.  Essentially this dicument said, make the vent stack short and keep it as warm as possible -- and they gave a number of options.

There has been a lot of success by putting a 3" to 4" transition in the attic just before the roof -- then going out onto the roof with a 4" pipe.  The larger pipe tends to frost over less.


The Insulation Solutions

Occasional ice capping can be driven away by simply wrapping a good quantity of fiberglass insulation (R-20) around the pipe in the attic space right up to the underside of the roof to keep the steam hotter longer. This is now relatively standard for new construction in cold climates -- and should probably the first and least expensive thing to try.

You could build an insulated box around the vent stack on the roof.  Far easier is to use an insulated flashing -- special vent stack flashings that have a foam insulation liner -- like an insulated Stack Jack Flashing from Thaler Metal Industries



A plumber in the cold American prairies took on the task of inventing an insulated termination for the plumbing stack.  He started with the idea of a vacuum thermos as a total vacuum is one of the best insulators we can have.  But that proved to be very difficult and expensive to produce.  So he tested out a double PVC pipe with a simple air space – as you can see in the photo.  The combination of a dead air space, warm gas coming up from the house and black paint on the outside to absorb heat from the sun gives tested temperatures that are almost magic: from minus 28 deg C outdoors to 4 deg C inside the dead air space and 9 deg C in the vent stack.  Woodring Plumbing seems to be getting great results in a prairie climate for only $50 US.


Heated Solutions

For those difficult cases where insulation isn't sufficient, buy some thermostatically controlled electric heating cables designed for cold-water pipes. Be careful on how you use these cables, they can cause fires. They come in 1-metre lengths for the smallest sizes and are approved for application to metal pipe (no insulation can be added over the heating cable). If your vent pipe is metal, the top foot inside the attic could be wrapped with this cable and the rest with insulation. The electric cable will keep the end of the vent pipe warm when the air outside is below 3 degrees Celsius. If the vent pipe is plastic, you could replace the upper portion with metal or go outside and add a foot of metal pipe which could then be wrapped in cable. With a bit more wiring, a cable could be installed without a thermostat and activated by a switch only when ice capping occurred. (Get a switch that has an "on" light to remind you to turn it off.) Never put such a cable inside the vent stack. These cables are not made to be explosion proof and there is methane gas inside that pipe.

The absolute solution is an ArcticVent, a product out of Ontario but which has proven its worth in Alaska and the Yukon.  This is a total replacement for the top of the plumbing stack.  It starts inside the attic, is connected to electricity inside the attic so there is no problem of running wires, has an explosion proof cable to deal with the presence of methane gas in the sewer gasses.  Being in the business, they have run into and dealt with one problem that no-one else has dealt with -- if you have a large block of ice in this pipe and suddenly heat it -- the ice block breaks free from the pipe and slams down to the basement, doing considerable damage when it lands.  So they have a retention system to hold the block there as it melts slowly.   It is expensive until they get to mass distribution but it is the one system that works in every environment all the time.


Help from Minnesota

The blog below has provided a most interesting solution from Mark in winter cold Minnesota:

"I live in Minnesota and used to have periodic problems with a frozen vent stack until my friend suggested taking a 1/2" diameter piece of PVC pipe (in my case about 9' long, but as long as you can make it before you run into your first elbow) with a PVC tee glued to one end of the pipe with short pieces of PVC pipe glued in each end of the tee to prevent it from falling down the vent stack. Drop this assembly down the stack (the tee prevents it from falling out of sight) and that's it. The warm air coming up the small pipe from inside the house keeps the vent stack from freezing over."

Now there's a creative solution, although I imagine it only works if there is no elbow inside the cold attic, allowing your pipe to get down to the heat of the house.  Thanks Mark.


The Sewer Skewer

In 2018 I was informed that Larry Villella from Minnesota turned this into a very interesting copper product – the Sewer Skewer  -- in 2022 it is available at the Home Depot is both the US and Canada. It is made out of copper and works exactly the same except probably more effective because of the metal.  It is a hollow pipe like Mark used but the interesting features are that there are exhaust holes in the wide cross piece on the top to let a little air flow, which can have the effect of bring heat to the top for defrosting. 

Also the metal cross pipe sticks out beyond the ice cap, and hence receives heat from the sun -- which can also initiate the defrosting.  So this has both the ability to bring heat from the stack below and profit from the sun when it is there, which gives you a good chance of eleminating the ice formed after a good storm.  They also offer multiple drop pipes and length extensions to get deeper into the stack.  If you look carefully, the rather expensive extension they sell could be made by you to any custom length - it is made out of standard copper plumbing parts and just screws into the fitting on the bottom of the Skewer.  

Overall - this looks like a great product at a reasonable price and easily available. If you are using this product, let us hear your experience in the blog below.  If this doesn't work. then upgrade to the product below which passively increases the heat fllow into the ice even when the stack is totally blocked.



September 2017 :  Darrel wrote in (see blog below) saying that he installed a device from and that it worked great.  So I contacted them, they sent me one and we talked a lot.  This is simply a brilliant device.  As you read above, Mark in Minnesota had the idea of using the warm air in the vent pipe to heat the very top of the stack using a PVC pipe and Sewer Skewer improved that using copper and reaching out to the sun.  The No Frost Venting company out of Manitoba takes this passive heating a giant step further, but of course it costs more. 

They have a closed loop copper pipe that extends down into the vent stack while the top of the device is a sealed tubular chamber which becomes a short extension to the plumbing stack.  This closed loop system is filled with refrigerant gas.  Refrigerant gas does its magic in refrigerators and heat pumps by changing from a liquid to a gas – and from a gas to a liquid – and in doing so it can efficiently move heat from one place to another.  Usually that phase change is accomplished with a motorized compressor – but in the NoFrostVenting device it uses the extreme temperature differences between the top rim of the plumbing stack and the air down in the protected part of the stack to boil and condense the gas passively.  The colder it gets, the better it works!  

With this device, some of the cold from the blowing wind that usually causes frost to seal off the plumbing stack actually condenses the gas into a liquid, which falls down to where it is warm enough to actually turn it back into a gas so the gas rises back up to the top.  Since the warm air is always rising in the stack, nothing freezes down inside the stack – but the upper rim is kept exceptionally and actively warm – hence no frost build-up to close off the plumbing stack. This is a system that is far less expensive than the electrically powered Artic Vent, and far more efficient than the Minnesota passive copper pipe.  A 24” residential unit sells for $295 and you simply pop it into your existing vent from the top.  


Help me to document the extent of this problem

In October of 2010 I added a blog to the bottom of this entry to provide a forum for people with this problem.  I want to encourage anyone who has experienced these sewage odours in the winter to make a quick blog entry -- especially if it is associated with ice capping. If there are enough of you we might even get some building code support in building houses to avoid these problems in the first place.  Local health departments tell me they get "some" complaints every year but I am sure that most people just don't know that this is something that is well known and has solutions.

If you try one of the above solutions, please let us all know where you live and how well it worked in your climate.  The codes are not moving, but the solutions are evolving.


Keywords: Codes, Foam, Frost, Basement, Freezing, Odours, Attic, Bathtub, Health, Ice, Insulation, Maintenance, Methane, Drains, Flashings, Gas, Shower, Sink, Trap, Valves, Vent Stack, Steam, Roof, System, Pipes, Plumbing, Problems, Smell, Ventilation

Article 851

Add A Comment

  Your Comments

Showing 151 comments

Viewing from newest to oldest – Reverse
Jack B on January 17, 2024 09:04

We’ve experienced an odor the last 3 out of 5 years with ice caps when the temperature is below zero for consecutive days. We have tried numerous solutions listed above with no resolve. The smell originates in our basement bathroom (which we happened to finish 3 years ago). We do not notice gurgling water but do notice lower water levels in toilets. We do have septic with an ejector pit in the basement (pit was installed/in use prior to basement finish). The ejector pit has been re-sealed and toilet been reset. Also have done a smoke test to pinpoint a leak (no leaks found). Vent stacks are 3” & 4”.

the original McTruck on January 14, 2024 19:12

Winnipeg is COLD right now, -40 C and the plumbing stack froze up. Same thing last year. I made an ice pick from a 12' construction nail and a broken pool cue handle, like a big ice pick. My long ladder is hanging on the inside of the fence close by, so no problem reaching the few feet from the edge of the roof to the stack to clear the ice on top of the opening. This time it didn't help, so I went back out and used the three foot handle on my "pick" to push a plug of snow or frost down the stack. Still didn't help. After looking online for answers, I found your site. A lot of silly and expensive ideas and no real good ones to solve the problem. I asked my wife for an old pillow case to wrap our $22 electric blanket in, and went down to the basement and wrapped the top of the plastic stack where it went through the floor up behind the bathroom wall. I turned it on high and left it for a few hours. The tub still gurgled when I flushed the toilet so I went back up to the roof. I noticed some steam was now coming out the top of the stack and the stack was now completely clear of ice. Next, I used the long handle on a push broom to push whatever was still partially clogging the stack down (about five more feet). There was no more gurgling and I left the electric blanket on for another day until the 40 below weather ends. This simple solution warmed the stack up from bottom to top. In the spring, I'll find out if there is a dead squirrel stuck down there. Hope this safe and inexpensive solution helps folks. Thanks, Frank.

Hello Frank,
Thanks for the story and glad it got you through the frost period. A couple of cautions.

First the heating pad itself -- they clearly state on the packaging that it should never be folded over on itself or boxed in as it could overheat, melt inside and short circuit the wires. Heating wires do exist for plumbing pipes, and are usually wrapped around the pipe in the attic where it is cold. It takes much less heat than heating from the basement and is fire wise safer. But if you can reach the top of the stack easily from a ladder, you probably don't have much attic space where the stack passes.

Second, remember the caution in the article that no heating wire is allowed inside the pipe, like dropping a roofing de-icing cable down the plumbing stack unless it is certified explosion proof -- there is methane gas in that pipe.

Third, before "forcing" anything down the plumbing stack, especially a big nail, be sure the stack does not have an elbow in the attic as many installations do. That could just punch a hole in the elbow and now you have sewer gas and methane filling your attic and filtering back down into the house.


Annette on September 13, 2023 07:51

Help needed. We have had sewer smell in our basement for years. Here is what’s happening, when temperatures get below 60 degrees in the fall or spring that is when it gets bad. It’s not freezing or snow. It’s dense cooler air seems to be causing the smell. Here is what we have tried: peppermint oil down the vent pipes to find the location of the leak, , smoke test, camera down all of our pipes and found nothing. Hired 3 plumbers and no one can help us. I will take any advice as we are desperate to fix this. We live in a 70s built home with septic tank with aeration system. . We have emptied the septic few times and did not help. We have ran water hose down all the vents and drains. We have also extended the 3” vent pipes on roof. All plumbing it’s pvc piping and we haven’t found evidence of a crack. If anyone has ANY advice we will take it. Thank you

lorne on July 27, 2023 11:25

New Vent system coming to market by Heat-Line

Robert Delorme on January 30, 2023 17:54

A lot of good solutions here, I need one for sure, all three of my toilets stopped working when snow completely covered my vent pipe. I got everything working fine but a two days later it came back. I can only think there is ice buildup. I'm going to try some insulation on the pipe in the attic. Questions: Do they not sell caps especially made for these vents or should they be left open to allow maximum air flow? I already have a 3 inch going right into a 2 inch so would a cap take some of that air away? Thanks for all this Jan!!

Hello Robert,
The top should be 3" if not 4" and open. A cap only helps to trap the ice. If you have 2" on the top, that will make it very easy for ice to close the hole. (Rain water into this pipe simply goes down the drain -- no need for a cap.) If you are below the snow level, then you will need to raise the pipe -- but not make it more narrow.

Jarrod on January 29, 2023 08:21

I live near Edmonton, Alberta, Canada. We sometimes get terrible sewer smells in our basement in the winter. Everytime I go around and dump some water in the less frequently used drains but I'm not sure it makes difference, the smell goes away eventually... Until next time.

I sure wish I had an extension ladder to get up on the roof and try pouring boiling water down the vent stack.

Hello Jarrod,
Try putting water in EVERY basement drain, not just the "less frequently used drains". Filling water into less frequently used drains is what is often done to compensate for evaporation, but syphoning caused by an ice cap on the main stack can pull the water out of any drain. Here is an article on evaporation from drains:
"...the smell goes away eventually..." tells me it is ice capping and not evaporation.

Kira on January 05, 2023 00:08

Edmonton, Alberta, updated 1935 two story home with finished basement. Before the plastic pipe ice-gapped only with extensive -40C temps. This year, after insulating and air sealing the attic + increasing ventilation, it is now happening at -30C temps or even higher when there is a lot of moisture. Cap is like a foot high now and house is very tall. Pipe was insulated inside the attic but that was not enough.

Hello Kira,
You have done the right things for the house, but apparently succeeded in cooling the stack pipe in the attic. You didn't say how much insulation you put on the stack pipe -- probably a lot less than on the floor of the attic. You could try seriously increasing the insulation on the stack, then wrap that in Tyvek to stop the ventilation from blowing into the fiberglass, which reduces the insulation's effectiveness. When that doesn't work, you need to try one of the top-of-the-stack-down solutions in the article above -- as noted in the article, some of them are working in climates colder than Edmonton.

Paul Celentano on December 26, 2022 01:21

Thanks! Great info. We've had this house for over 30 years and whenever we'd get a cold snap below 10 degrees F, the bathtub gurgles loudly when the toilet flushed. Ice in the soil pipe would explain that. With no access under the roof, I might try the Sewer Skewer and or the double PVC method of wrapping the stack above the roof. Even if I do nothing, it is good to know the cause. Thanks again!

Jason Dauenhauer on March 12, 2022 15:49

I live in Northern NY state and have experienced both ice capping on our septic vent as well as fumes (year round) depending on which way the wind is blowing. However, my vent stack is horizontal on the north side of the house. Do the carbon filters and ice prevention products work on these applications the same as vertical vents? Could I be so lucky to acquire a product that prevents ice and controls fumes, or would I need to switch them out during the various seasons--Ice control in the winter, but live with fumes...thanks for any suggestions.

Hello Jason,

Air vents, like septic and plumbing stacks, that vent vertically up are generally free from wind problems, unless the landscaping around the house causes wind to blow down on the roof. When wind blows over a vertical air vent, it actually creates a slight suction that draws air out. The very reason these vents are always on the roof is to allow those odors to dissipate before reaching a window or a patio or any air intake duct.

Horizontal air vents, even bathroom and kitchen exhaust ducts, become subject to important input pressure or output suction depending on the wind direction. Those problems are usually countered with power fans and back draft dampers. With a passive air vent, such as plumbing vents, the wind can seriously unbalance things, and probably relates to your odor problems.

If you can't reorganize the stack to avoid odor control you might want to use carbon filters very low in the piping, actually on the warm side of any insulation so the filter will never freeze and then use the exit warming devices to prevent ice capping on the totally exposed exit point. Remember, you can't just put roof electrical heating wires at the exit, as any wires are required to be explosion proof -- there is methane gas in a septic system.


Dale MacFarlane on March 05, 2022 15:24

It has been 7 years of battling this problem of vent stack ice capping. I think this year I found the solution! (Sorry for the long story but I think you'll find it is worth it).
My situation - Old house was moved on a new basement in 2012 in southern Saskatchewan. A new ABS stack was put in almost to the attic, where the original cast pipe was retained. Sewer smells during cold came from outside the house, falling down the roof and into the attached garage and making it way into the basement through any open door or opening, settling in still areas. I am on gravity sewer, but most others in my Hamlet pump into the sewer. When they do, the fumes are concentrated and potent and the manhole is across the intersection! Combine that with cold weather and the smells surrounded and entered my house. Whew!
Here's what I have done UNSUCCESSFULLY to date.
1. Put heat tape on the 2" cast iron pipe in the attic. This pipe then opened up to 4" at the roof line. It would still frost over.
2. Extended the pipe above the roofline about 18". No success.
3. Replaced the cast iron with 4" ABS (which was already about 2' below the ceiling so I just extended it through the attic and roof, about 8' added).
4. Insulated the ABS pipe. My theory was that the attic space would cool the air so much that by the time it reached the roof it was just wafting out and so froze more easily. I also put a diverter in front of the gable vent to redirect the outside air around the stack which was only a couple feet away from the vent. No success.
5. Even though they say not to, I put the heat tape around the ABS (above the insulation) to see if the combination would keep the air warm enough. Nope.
6. I made a "T" out of 3/4" copper pipe. I flattened the outer ends of the T and soldered them shut. I drilled some holes on the underside of the T, and extended the pipe down the stack 12' to bring warm air up through the copper and hopefully vent warm air into the top of the stack. No success.

This year I got smart (I think!). After again risking my life to constantly clear the roof stack, I went into the attic and cut a "Y" into the 4" ABS stack just above the insulation. One side of the "Y" went straight up and outside, with the other one going out at an angle, to which I added an elbow to make it also go straight up. On this elbow I mounted an Oatey Air Admittance Valve (AAV),3in-4in,500 Dfu Model: 39223. This is the key to the solution!! Then at the roof I reduced the straight up 4" main stack to a 2" opening. This gave me an outside main stack vent to meet code, but reduced the amount of air that would exit the stack. With the AAV and the 2" stack there is still plenty of air that can be drawn into the system to keep P-traps etc. from emptying, but it limits the amount of air that can waft out. Now, if the 2" pipe on the roof was to freeze over solid the system can still draw through the AAV in the attic. Since I made these changes I have had no problems (down to -27C) but the temps have not gotten back down to -40C so I don't know for sure - I do think I have the problem beat though! Interestingly even at -27C the 2" vent has not frozen over.

Here's hoping for a smell free next year!!!!

Hello Dale,

Very interesting! I like your solution but I am trying to think of what might go wrong -- although I don't believe anyone has ever scientifically studied using an AAV in the attic instead of an open stack. The one concern that comes to mind is that a 3 or 4 inch AAV probably requires more pressure to open, than the resistance of a P trap under a sink or tub. Usually AAV valves are sized to the trap they are supplying air to. This could cause some giggling or empty drains when there is a large flow from a sink or tub and the AAV doesn't open, so the unused trap does. You might actually test that by capping of the main stack, like an ice cap would do, and try various draining scenarios in the house which would require the AAV to go into action.

Let us all know what you learn with time and temperature.


Laurel Anderson-McCallum on February 25, 2022 10:34

9:24 a.m.
When I first had my roof cleared of snow here in Winnipeg the fellows found the stack was badly frozen. So they poured a lot of boiling water down and the gurgling after the toilet flushing stopped. My eye infections seem to go down, which I later understood could be related to gases in the house. The the noises came back a couple of months later and I realized the stock was probably frozen again. I had to get another company to come out and do it, but they were very fast...five minutes, maybe seven and poured one kettle of boiling water down the stack and said that it was clear all the way to the bottom. However the noise after the toilet flushing did not go away. So I have purchased a sewer skewer and it will be arriving soon. I hope to get somebody to go up there and drop it into the stack. In the meantime, the company said there's probably something wrong with my plumbing and they're not coming back.I wonder if this is the case or whether they should have put more water down there and I should press the issue. I really thank you for the column that you've written and all the information and help you have given. I will probably endeavour to get the stack cleared once more or warmed up. Thank you.

Hello Laurel,

If the Sewer Skewer keeps the stack open, but you still get gurgling, you should have a plumber snake the stack from the toilet to the stack and then from the roof to the basement. You may have a birds nest down there somewhere.

Come back here and let us all know how it comes out.


Rob on February 23, 2022 07:11

Can a mechanical air vent be installed on a horizontal vent pipe in an attic? We live in Saskatchewan where it gets to minus 40 often. Our roof vent plugs often and is not easily accessible in the winter. Would the mechanical air freeze up in the cold attic? Any thoughts would be appreciated.

Hello Rob,

Not a good idea simply because in-line fans are round, and on a horizontal run, the bottom part fills with moisture and freezes -- actually freezing the impeller. You can install one on the vertical part of the pipe -- but (the 64 thousand dollar BUT) -- it must be explosion proof! There is methane gas in a plumbing vent pipe and that requires motors, wiring, switching -- all "explosion proof".

There are several proven solutions listed in the article above. If you want the all climate fool proof, but expensive, solution -- buy the ArticVent.


Blake on February 05, 2022 11:47

I live in Narol, Manitoba. Every winter I get ice capping on my vent stacks. One is accessible from the ground where I use a roof rake to keep the snow clear, the other vent is to high up. I have looked at options to fix this problem but not sure which one to go with. I agree with Jan that this should be added into the building code to eliminate this issue for home owners.

Tyrel on January 28, 2022 21:54

We just bought our first house. 2nd winter in it (northern Wisconsin). We get the septic smell mid-way through the winter in our only basement floor drain but it still has water. I'm thinking it's the 4" vent out the roof partially freezing and will be insulating the part in the attic. Unfortunately it's far to steep of a pitch and too icy to safely get on the roof to pour boiling water to verify it's the vent. What is throwing me off is we don't have any gurgling or drain issues with any drains around the house. Would a partial closure be enough to divert the septic gas back into the basement but still let airflow for draining? Appreciate the info and it's very comforting to hear other people with the issue and solutions, plumbers around here haven't been much help.

Hello Tyrel,
With no drain problems, it is probably not the plumbing stack. A wild shot -- Could a clothes dryer and a bathroom fan be creating a vacuum in closed basement which could suck air up through the floor trap without having it lose any water?


Mario on January 13, 2022 12:09

We live in Eastern Pennsylvania in the Pocono Mountains and we're getting bad odors from our septic system in our basement. It's not an evaporation issue, as all the traps in the basement get regular use, and I don't think our roof vents are frozen over (it's currently a little too icy to go up and verify right now, but I've checked in the past when it's gotten bad and never seen any ice or obstructions). It's worse in the winter but happens occasionally in the warmer months as well, and it's usually worst when doing laundry or running a shower.

Is it possible the cold air above the vent is actually pushing down and creating a reverse air flow, not allowing the warm gases to escape? Similar to how a chimney flue sometimes doesn't properly allow smoke to ventilate until it's sufficiently warm?

I'm wondering if installing these vent pipe fans might help maintain a proper upward airflow in our roof vents? (

Any advice is greatly appreciated. I've had the septic pumped, smoke tests performed, and several other supposed septic specialists check it out and offer no tangible solutions.

Hello Mario,
The idea of a power fan is interesting. My only concern is that the company is located in Texas, not exactly ice capping country. Also their concern for having a cap to prevent debris shows they have no ice capping experience but they have had debris fall in on the impeller. I think it could work, but I would install it warmly inside the house, and maybe on a horizontal run that could get no debris, or ice falling into the impeller. If an ice cap did form on the top, this could actually push the odors into the plumbing traps. If you try it, let us know if it works and I will list it with the solutions.

Tracy on January 11, 2022 14:24

Thought the pvc pipe hadn’t worked as there was ice buildup. I went up with insulation to put around the pipe after the -45 days were done and found that the ice was only a thin ridge around the edges. The center was completely open. So yes, the ten feet of 1/2 “ pvc pipe down the stack works!

Hello Tracy,
Thanks for the follow-up. Bringing heat from deep in the house up through an ice cap makes for a heat flow, which sometimes can win the war!

Joe on January 10, 2022 20:52

Shot the PVC pipe with a pellet gun. Knocked the ice cap off enough to start working again.

Hi Joe,
I guess that's better than breaking a leg on a slippery roof! You may want to reinforce the PVC against pellet shock for next season?

Thanks for the very novel solution.


Justin Bouchard on January 06, 2022 19:23

I fill my bath tub with hot water let it drain. If I need to I will repeat 2-3 times. But usually does the trick

Hello Justin,
Yes, for a light case of ice capping, continuous hot steam can overcome the ice. In colder weather the hot steam sometimes just makes it worse. Glad that something so simple is working for you.


Tracy on January 05, 2022 17:51

10:30 last night this 59 yr old woman In Brandon, MB, was climbing the icy roof to knock the ice off the vent and pour hot water down. It’s -40 and I just got back in from doing it again this afternoon. I am very grateful for your suggestions on a permanent solution. I’ll be back up there tomorrow to insulate three pipes and put the skewer down them!

Finally got up there today and the vent was almost closed again! I had Shark Bite pvc 1/2 “ hose still on hand from years of being a landlord, so used that as the commercial products suggested weren’t available in town. Drilled holes in the end of a 10’ length, put twine through it and went up there with gorilla tape to tape the ends of the twine to the pipe. Note to the creative diyers out there, gorilla tape doesn’t stick to itself at -24. Wrapped it around 5 times anyway then used zip ties to secure it all to the pipe.

I can’t thank you enough, Jon, for having this site available and for the help it’s been. You’re a gentleman and a scholar as well as a contractor!

Tracy on January 01, 2022 15:01

10:30 last night this 59 yr old woman In Brandon, MB, was climbing the icy roof to knock the ice off the vent and pour hot water down. It’s -40 and I just got back in from doing it again this afternoon. I am very grateful for your suggestions on a permanent solution. I’ll be back up there tomorrow to insulate three pipes and put the skewer down them!

Hello Tracy,
What courage! Do what you can now and follow the results -- then if not good enough, move on to one of the other solutions. The Artic Vent is perfect, but expensive. The No Frost Venting - passive refrigerant gas device is very effective in Manitoba.

Let us all know how it goes.


Fred on September 21, 2021 11:59

"Mineral Oil, found in drug stores, is bio degradable"
Please see the web...mineral oil is a petroleum product that is not biodegradable.

Hello Fred,
A good point. Several sources consider it slowly bio-degradable but its real characteristics that are useful here is that it is without any odour, will not go rancid, evaporates extremely slowly and is really non-toxic. That last point is demonstrated by it being recommended to ingest for constipation. Thanks for the precision, I will include that in the article.

Bert Jackson on October 07, 2020 17:35

Excellent information! We have lived in our home for three years and every winter have a sewer gas odor coming from the sink in a half-bath. We called a plumber and he said the only way to find the problem was with a smoke test. That didn’t seem necessary to me since we knew where the smell was coming from. It seems likely that ice or snow in the vent is causing the problem. There are three plumbing vent pipes on the roof--one 3" and two 4". (Information provided by a person cleaning the gutters.) Is there any way to know which vent is associated with that bathroom sink other than having someone get on the roof when we are having the problem, obviously a dangerous time to be on a steep snow and ice covered roof? (Two of the pipes are about equal distance from the problem sink and both are on the north side of our house.)

Hello Bert,
A smoke stream injected into the drain line beyond the water in the sink trap will show up immediately coming out one of those stacks on the roof. You can do that without climbing on the roof. If you can get on the roof -- run a hose down one of the stacks and listen for the water at the sink or tub next to the sink. That is not as precise but it can work.

Amber Lubig on December 10, 2019 18:35

We have this problem every year, stack on top of the house freezes over whenever it starts getting past -25 C especially because we live around a lot of farms and the wind is insane. It’s so frustrating that they don’t take this more into consideration when building. Thanks for the tips definitely going to try one of these out.

Dave S on October 07, 2019 08:54

I live in Central Vermont, and my vent freezes over when it gets below 0 degrees F. Enough air still gets through for normal household use, I don't get odors, but I have a 250-gallon siphon chamber after the septic tank, and when that empties, air is sucked through both toilets for about 30 seconds, presumably because not enough volume can come through the vent. I insulated the vent through the attic and painted the outside flat black, but still get icing. I'm going to try a home-made Sewer Skewer next. It looks like they close the short ends of the tee and just have a few small (1/4"?) holes drilled. It seems to me it would be better to leave the ends of the tee open, anyone have any thoughts on this?

Cody on April 12, 2019 10:04

I had consent issues with the plumber the general contractor used as a sub, I would have been better off being my own gc. The 15% upcharge alone most contractors charge is not worth it, let alone when they are not actively checking the work they and their subs are doing. Needless to say the vent issue I have is the plumber ran everything right (took months and would not show up on days his company was suppose to) and just let it vent into the attic. I called them and they came out to fix it, well instead of actually fixing it they just capped it. It was my fault for seeing them work on it and not checking it. I figured I would find out how to do it on my own. Sladek plumbing in New Jersey failed on this one, and somehow my town passed it!

Hello Cody,
In Canada that would have rotten out the roof in a year and the plumber would have been on the hook for the whole top of the house! Unfortunately I have run into some very sincere contractors who just thought that there was a lot of air in the attic and that will work fine. We have a long ways to go to get the whole workforce understand the basics of building science.

Mike B on January 26, 2019 11:46

I live in northern Ontario.
It has been between -23 and -40 c this winter.
Both my vent stacks (3" pvc) freeze every winter. I live in a rural town and we have a field bed if it matters.
Further the issue / I have about 2.5' of snow now and my vent is only sticking out 4" right now. My roof is too step to shovel so I'm gonna have to extend the pipes even just temporarily for this winter.
FYI the stack freezes several times a winter.

Hello Mike,
There are a wide variety of solutions and prices listed in the article above. I am sure you can find something there to fix the problem as many other people have. One last time on the roof!

Good luck

Ron Zielinski on January 21, 2019 21:34

Sewer gas smell. We have a new house house (3 months old) and just had first bout of below zero weather. Next day after zero weather the house smelled like the septic system. I am going to check the vent stack for ice but noticed the greatest smell was from the basement sump which only runs about every 11 days when the water softener regenerates. It did not smell prior to the below zero weather. The sump lid is sealed, caulked and screwed in. Is the problem from the sump?

Hi Ron,
Sumps don't usually smell of the septic system. If your sump is vented to the vent stack, then it is connected to the sewage system. Where does the sump discharge to, and is that path ice free? Here is a link to good information on the sump pump pit:


sewerskewer on January 02, 2019 08:02

Nice information..! If you are looking Clear Frozen Sewer Vent service .Contact us

sewerskewer on October 16, 2018 02:49

Thanks for this informative site! We have been very cold for the last 10 years or so in Helena, MT, with mostly 20-30 below F at night and highs single digits F. All my vents have covered with ice and I tried lot but failed every time, but as I read your article I found sewers Kewer that helped me to come out from that situation. Thanks a lot
Read More:-

Hello SewerSkewer,
With a name like that I would assume you had something to do with this product. It looks great to me and less expensive than my favorite solution to date: the NoFrostVenting. Probably start with this and if it doesn't work move on to the one with refrigerant gas doing the work.

Tom Gilmour on March 19, 2018 14:40

I live on the 2nd floor of a 3 floor condo in the lower Laurentians. When the owner above me uses water my kitchen sink gurgles. My solution to silence it is to simply close the plug of the drains. Since the sink has no overflow this works to silence the gurgling sound.

Guy on March 01, 2018 05:56

over 55
i live in an over 55 community, and have experienced sewer gas . I would think that a community such as our should have protection of sewer gas exposures. It maybe not harmful , but when the gas is exposed to communities like were over 55 should have protection against these exposes to these gases.

Hello Guy,
All sewage systems vent out the top of the house on the basis that that is high enough to disperse sewer gas thoroughly before any can notice it. If you are smelling this outdoors, it may be caused by weather inversions pushing gas, wood smoke etc back down. It can also be caused by overloaded leaching fields if you are not on a municipal sewage system. Ice Capping only causes sewer odours inside the house. If every house has this problem, and they are all made the same, someone needs to really study the solutions presented in this web page.

Carol on February 23, 2018 19:23

We're getting an occasional relatively small back up in one of our drains. We're in Alaska, no issues in the summer. Could this be a frozen vent issue? We've had the system looked at, and no one seems to have answers.

Hello Carol,
Usually a backup is caused by resistance in the line downstream of the drain that is backing up. Typically Ice Capping causes the siphon traps to empty, leaving bad odors in the house. It does however make the whole system a bit sluggish, so if your water source is upstream from this drain, it could be the cause of the problem.

Gary G on February 20, 2018 21:17

I have a neighbor who is having the ice clogging or snow coning on the vent stack pipe in northern wisconsin. I was wondering if the vent stack pipe could be routed out the gable end vs. through the roof.

Hello Gary, That might help with the ice, but it is not allowed by building codes because it would interfere with the proper functioning of the ventilation system. The wind could blow directly into the vent or cause a suction on the vent -- all disturbing the air flow. By going vertically up on the outside the wind causes a slight suction all the time. You are better off using one of the solutions discussed in this blog.

Jim McVicar on January 09, 2018 13:52

Thanks for this. I'm going to try some of the suggestions. We live in New Brunswick, on the Bay of Fundy. High humidity and cold, windy winters. The past week has gone as low as -24 celcius.

Last week, our bath started gurgling every time we flushed the toilet. Eventually, gas smells entered the room. I went up to the roof to find both of our 4' stacks blocked with hard, crusty snow. I poured hot water down both and the problem went away. This week, we had another wet snow storm followed by freezing rain and the gurgling started again.

All that said, I may have discovered the issue. The previous owner (we bought it last summer) had installed all new lighting in the ceilings. He removed much of the attic insulation to do the wiring and never got around to putting it back. Aside from the obvious amount of energy I'm wasting, I'm hoping putting the insulation will fix the stack issue. I'm also going to wrap the pipe under the roof.

Cross your fingers and thank again for the article.


MN Guy on January 09, 2018 09:55

This is the first year we've owned this house, but it is built very soundly with good energy conservation principles in play. We have master bath that is in it's own extension on the north side of the house. The attic space above it is very well insulated. With the 2 weeks of -20F temps in MN this holiday season, we've frozen the vent.

Frank on January 07, 2018 22:25

I have a newer built home (4 years old) with a 4” vent stack (similar to one in your photo). For this first time ever, I have gurgling from by shower drains in both my second floor bathrooms whenever I flush the toilet. Although I can’t see the vent stack well, I assume some ice is built up given it’s been two weeks of extremely cold weather in MTL.

Hello Frank,

Montreal has generally not had stack freezing problems but this year I have had quite a few complaints. One detail about Montreal is unusually high humidity in winter air -- so hit that with unusually drawn out cold spells, and the frost can start to build on the rim of the stack. I guess it is time to start to profit from all the prairie experience listed above.

Jim Scott on January 06, 2018 10:20

I grew up near Prince Albert, SK in a 2 story house. The plumbing stack never froze up. Later my folks moved to a single story house. Then there was occasional stack freezing.

One of the older citizens in town told me that stack in 2 story houses never freezes but the stack in single story house can freeze. That's not proof of anything but I have found that many of these more experienced people know what they are talking about.

Don't know why two stories houses experience fewer freezes but it might be that the 2 story house has a greater stack effect that pulls warm air out of the sewer system.

Hello Jim,

Definitely a two story house has a greater stack effect, hence more warm air moving out the top. But also there is more pipe to warm up in the walls, so the rising air is warmer from that effect as well. In basement studies related to radon, an 8 foot passive vent stack moves no air.

Diana Drobnica on January 03, 2018 10:16

We get ice capping. Strange thing is we lived here 20 years before it became a problem. I intend to try some of your suggestions. Thank you for this informative article.

Try to think of what you changed just before it started freezing.

One thing we are just getting information on is people on septic systems who vent the tank at ground level don't get warm air through the house plumbing stack, and hence have more ice capping. Close the venting at ground level.

Greg on January 01, 2018 11:11

We live in Western New York and have had this problem since moving into this house 6 years ago. It wasn't until I read articles such as this that I realized why we get sewer odors in cold weather. When the weather breaks we will try some of these solutions. Thank You!

Nikki D. on December 31, 2017 06:52

I live in Shefford Quebec, at 1000 feet elevation, on a western slope of a mountain and I have the problem with the vent pipe on the roof blocking with ice cap when temperatures goes for too long below 10F and these days under 0F. In 10 years living in my house it happened a few times only, but that daily smell, coming and going in the bathroom is terrible and I was also afraid for our health. The roof is too high, so impossible to climb without special ladders and too dangerous. Will have to wait until it melts and in spring choosing the best solution, not too expensive. thanks for this blog, very good information and nice to know that I am not alone.

Carl Wilkins on December 27, 2017 18:54

Mike, I live in Minnesota and each winter, when below zero occurs, my vent ice caps. I’m 73 so my getting on the ladder concerns my wife. It appears there is a universal problem in colder climates.

Hello Mike,
And now some solutions as noted above.

Phil.W on December 26, 2017 11:59

trying the 1/2 pvc with T fitting at the top (shaved down part of the pvc for the T on either end I have sticking out so it sits on the stack perfectly and can't slide or just pop out) from Winnipeg. Will update if it doesn't work. For myself I have an issue where I have old cast iron stack along with no insulation in the attic on the pipe and it reduces when it comes out of the roofline. I raised the stack last year which stopped me from having to constantly go up but on days like this where the weather is constantly sitting below 30 and there was snow I guess it froze over.

Mary Shipp on November 08, 2017 13:57

I live in Northeast Montana and we have lived in this house for 9 years now. We have had this smell from day one and not only in the winter, we can also get it in the summer, especially if I wash clothes and the washer goes on spin to drain the water. I'm frustrated. We've had a plumber out here 4 times, different plumbers and each one kind of skirts around the problem but finds something to simple to do to charge us. Anyone else get this smell in the summer when washing clothes?

Hello Mary, This is probably un-dissolved soap from cold water washing. Nothing to do with the plumbing stack. See

Darrel on September 23, 2017 15:04

I installed the no frost venting 24" vent kit last winter. Worked great.

Doug Findlay on April 05, 2017 22:13

WE live in Ssakatoon saskatchewan and have always had our roof vent freeze up several times a winter.We have lived here 49 years in htis house. Ithought it was because the vent terminated at th roof line so when we reshingled 2 years ago I had the roof vent extended about 2 feeta bove the roof line to prevaent snow from blocking the vent. This January I was up on the roof every 2 days pouring boiling water down to melt the ice. On night our methane gas alarm went off and you could smell sewer gas. I read about the 1/2 inch abs pipe trick and thought I would try it. The vent has not plugged up since. I went up once to check it on a minus 30 day and there was a layer of frost around the 1/2 inch pipe but there was no sewer gas smell. I am gld i dont have to go up so often as I am76. I had anchor points installed at the roof peak and have a rope down to the eaves so ther is something to hang onto. Thanks for having this forum . The pipe worked for me.

Dennis M. on February 04, 2017 13:26

I live in Westtown NY, hour north of NY city. On cold days, below freezing, after I take a hot shower, I have that delightful aroma in my basement. I have camered my system, pumped my tank, cleaned the vent pipes, all to no avail. In addition I have a charcoal filter on the vent stacks, which I also changed out. This ice capping thing is what I think is happening. The hot water gets into the charcoal and it freezes blocking the pipe. My question is how does the smell get into my house. It shows up in my office, no plumbing, and under the intake vent for the air conditioning system. I have sniffed every bathroom fixture, washing machine, everything. I am also wondering if I should remove the charcoal filter. Thoughts anyone? Thanks

Hello Dennis,

Filters on a plumbing vent system are doomed to ice up if they are high up in the system. Don't need filters -- all the nasty odours are supposed to go out above the roof.
As for the air conditioning system, you probably have a condensate drain tube leading to a drain. That needs to have a vertical loop in it, to keep some water in the tube just like a sink's P trap. If the tube is straight and empty it will always bring odours into the house, even if the vent stack is not frozen. By the way, the same goes for Heat Recovery Ventilators with condensate drains.

Jeff H on January 30, 2017 11:59

We're in Saskatchewan, where we can routinely expect a couple of stretches of -30 to 35 C weather in any given winter, and we may well have had this problem before, but I first became aware of it in a cold snap a couple of weeks ago- didn't get as far as smelling sewer gas in the house, but we started hearing a strange gurgle from the tub every time we flushed the toilet. Checked the stack, and sure enough, it was almost completely blocked with ice. As far as traps that dry out, I work in a building that has in-floor heating in the slab, and we have had issues at times with traps on floor drains drying out and letting sewer gas into the bldg- for a while we tried to remember to have someone pour some water down the drain every so often, then someone suggested pouring a bit of cooking oil in the drain- it sits on top of the water and prevents evaporation.

Hi Jeff,
Oil in the traps works to prevent evaporation, but use mineral oil rather than cooking oil -- it will not go rancid!
The permenant mechanical solution is a Dranjer dry valve, invented right next to you in Winnipeg -- just look up Dranjer in the keyword list on my search page.

Jon Eakes on January 28, 2017 15:43

I got a letter from Jeanne Vogel who is trying out the FrostFree Sewer Vent device discussed in the article above.

Hi Jon, Thanks for this information. We installed the thermos vent stack this year and this is the first year since we built our cottage in 2012 that we haven't had sewer gas in the house. I could kiss you! Not really, but thanks so much. What a simple solution. -- Jeanne

I'm not opposed to being paid in kisses.... - jon

Scott Barnes on January 23, 2017 15:07

Thanks for this informative site! We have been very cold for the last 6 weeks or so in Helena, MT, with mostly 10-20 below F at night and highs single digits F. My three vents have iced over. Tried the 'PVC T' trick first on one of them, didn't work, it iced over inside the 'T' mostly. I have drilled a large hole in the top of the T to let the gas go straight up, don't know if that will help or not. I insulated the 1-1/2' vent pipes in the attic space (Big Hassle, but it's done). Bought 2 of the South Dakota stacks described in your article, they are very nice, and I think they along with the insulation will solve it! On the third stack I put a piece of ADS black corrugated pipe around my existing 3" PVC stack. This seems to do pretty much the same thing as the South Dakota stack, insulates and is black. It has been working fine for 3 weeks of this cold. I just happened to have a piece of it laying around.

Jonathan Wright on January 17, 2017 10:34

I live in Iqaluit, Nunavut, where the temperature peaks at -30 C for at least two to three months of the year. Our stacks freeze solid of course in that cold, and the best soution we've come up with is using the 3/4" copper tee. It's not perfect, but it's the best anyone's come up with. Most of our houses are on trucked services which means our traps are sucked completely dry everyday by the sewage truck if our stack is blocked. We don't have municipal in-ground sewer plubing because of the permafrost, and we therefore use above ground inuslated holding tanks for our sewage which need to be pumped out daily or they freeze solid. So all that to say, this problem affects us in the Arctic much more than you guys in the balmy South!

I've toyed with large 3" air admittance valves so that the sewage truck doesn't at least suck our traps dry, but their vacuum pumpe are so powerful, that multiple AAVs can keep up with the airflow. Only an unobstructed stack can do that.

I might add that this whole thing only became an issue when we switched to ABS from the old iron stacks. The metal used to conduct the heat from the house and kept the stack clear even in -40 C! We need to revisit code, especially here up North.

Hi Johathan,
I always knew that loosing cast iron plumbing stacks was terrible for water flow noise problems, and now I see it has an effect on simple conductivity. But I imagine that weight of transporting cast iron pipes compared to ABS makes quite a cost difference. I assume you took a look at the ArticVent above. Costly, but a guaranteed solution.

Randy on January 06, 2017 15:00

I like the suggestions to run a small diameter PVC or copper tee down the stack - this is an interesting fix. But trying to get my brain around it - the warm air coming up the small pipe from inside the house is the same as the warm air coming up the stack. Does the smaller pipe stay warmer because the stack pipe is "shielding" it from the elements? Not suggesting this doesn't work (and thanks to the posters here for providing the tip) but just wondering how this works.

Hi Randy,
I believe people who say it works, but like you the only thing I can figure is that the shielding provided by the main stack allows this one to maintain warm air flow through an ice plug, and hence warm air can continue to rise and under warmer conditions melt off the ice cap from the centre out.

Tad Everhart on January 04, 2017 00:58

Caveat: I'm not a plumber, code official, or expert in buildings in your climate. However, you might consider installing air admittance valves within the conditioned space of your home instead of the through-roof vent pipes. These simple one-way valves are used widely in Europe and are allowed in all manufactured homes in the US (which are manufactured subject to the USA's HUD code instead of local building codes). I installed them in my house as part of our Passive House retrofit because by replacing the pipes through the attic and roof, they eliminate cracks and seams where warm air can escape in winter (because warm air rises as it is displaced by colder, denser, and heavier air). At the same time, eliminating through-roof waste pipe plumbing pipes prevents cold air falling down into these pipes into your home and cooling the portion of your house you want warm. In fact, it is likely this cold air that is displacing the warm moist air that it rising, condensing, freezing, and blocking your vent pipes. The air admittance valves (AAV) are one-way valves that allow make up air in the drain pipes when water falling down the pipes pulls air with it. However, they do not let the sewer gases come into your home. In order to address the potential for positive pressure from the municipal sewer system disrupting the water in the traps and blowing sewer smells into our house, we installed a simple, activated charcoal filtered two-way valve in the clean out just outside our foundation. This is the way Europeans build new energy-efficient homes. And HUD allows it in all manufactured homes. Some local building codes and building officials may not allow AAVs or place restrictions on their use which are unsupported by science. However, far-sighted jurisdictions like our City of Portland, Oregon are changing that with the support of manufacturers like IPS/Studor. You can read the case study at BTW, there are lots of other good reasons to use AAVs instead of through-roof vent pipes including fewer falls by plumbers, fewer leaks in roofs, less pipe to manufacture and purchase, less labor for installing unnecessary pipe, fewer penetrations in roofing, and fewer obstructions for rooftop solar.

Hello Tad,

Vent Valves or Air Admittance Valves are generally tolerated but frowned upon by plumbing inspectors in Canada -- while outright banned for toilet lines. The frowning comes from using cheap valves and getting bugs caught in the closing mechanism which then holds them open and allows free flow of gas into the house. At the same time I know for a fact that over 100,000 of these devices are sold in Quebec alone each year! With greater energy efficiency in construction it is tempting to eliminate the vent stack -- but then again, as the house gets tighter, there is greater potential that a clothes dryer fan may just draw its air from the plumbing system if this becomes the easiest source of air. That's called shooting yourself in the foot. Is anyone else out there having any luck with inspectors on this possible "total solution" for cold climates? You can go here to see what we are talking about:

Tim on December 27, 2016 23:35

For a temporary solution I've used a hair blower to blow hot air into the stack via the washing machine drain pipe which is located near one of the smaller diameter vent system pipes. I take the washing machine hose out of the drain and direct the hair blower into the drain. A piece of wire can be used to hold the dryer in place. The time it takes to melt the ice cap varies depending on the size of the vent system and the distance from the warm air to the main stack (in my case between 45 - 60 minutes). I've never run into a large chunk of ice dropping down and damaging the pipes but it may be something to consider if the system has been plugged for a long time.
I'm in northern Ontario and will be insulating the main stack in the attic this spring.

Scott on December 19, 2016 11:47

We live in Southern WI, and last year (2015) was the first time in 15 years that we had this ice capping issue. Last week we had it happen again. We have had very cold temperatures, and a little relief coming around Christmas. I had our septic pumped in October and was informed that the outlet was plugged and needed to be taken care of next spring. Also in 2012 we remodeled our master bedroom (where the vent goes through to roof) and insulated the ceiling very well. After poking through the vent to break the ice I saw some vapor come out. This morning I notice the ice cap forming again, and a little vapor coming out and figure it is a matter of time for it to close off (temps in -14 this morning). The vent is about 3 foot from the part of the roof, and about 6-8 foot from peak. The vent is only 5" above the roof boot. I was thinking of extending the vent to about 12=18" above the roof boot. I like the idea about the smaller PVC inside with the Tee on top. Just curious if that works? I will also put a coat of grease on the extension pipe I do. The pipe is 3". Would cutting the top of the vent to an upside down "V" (point sticking up) help any? Guess I will try the extension and grease at the top and hope for the best. Getting tired of climbing up the roof.

Hello Scott,
I would really suggest that you try the FrostFree stack extension shown above. It comes from not so far from you. And if you do use it, please come back and tell us all how it went.

Brian on December 17, 2016 12:03

I live in northern Ontario and experienced ice capping for several years. My vents extended only a couple inches above my roof decking. I seem to have solved my problem by insulating the vent pipes in the attic and adding a 3" street 90 elbow and a 45 to the 3" stubs sticking thru my roof. I think these elbows trap a bit of heat inside the pipe preventing the vents from fully freezing over. Did this 2 years ago and so far so good.

Hello Brian
This sounds like a gooseneck vent - which I assume stands above the snow level? Interesting, send me a photo.

Aaron on December 16, 2016 17:23

I live in the Twin Cities in MN in a newer home. All three vents freeze over every year. Plumbers have no solution. Vents are not insulated in the attic nor above the roof line. Often gets -10 to -20 for a stretch each winter. Could I install a condenser, conceptually similar to an air conditioner, to take the moister out of the air before it leaves the heated portion of the home?

Hello Aaron,
I have not heard of any condenser efforts working. One reason may be that often a lot of the moisture that turns to ice comes from the outdoors, usually in the form of snow or freezing rain. This was shown by one contractor in Winnipeg who claims to have solved many ice capping problems with freestanding wind deflectors up-wind of the vent.

Peter Stokinger on December 13, 2016 15:34

Located in Wasilla, Alaska. Brand new house, 1400 sq ft ranch, 3 BR 2Baths. Sewer smell comes and goes. Had builder out yesterday to check why and found all three of our vents frozen shut. Cleared all out and smell stopped. They are considering insulating two of the three up throught the attic to the roof to help. They are not sure this will help, but!! Any suggestions?

Hello Peter,
In your neck of the woods all vent stacks should be heavily insulated in the attic, and you will see above two ways to even insulate the part on top of the roof. But there are some places where the wetness of the snow and the cold winds require expensive solutions like the Artic Vent -- last one in the article above.


Mark on December 09, 2016 17:42

The suggestion from Minnesota using technology 1/2" PVC with "T". Are you putting caps on the "T"?

Jen on December 09, 2016 16:57

We have had sewer smell only once it gets below 0 but never constant, comes from basement shower only, So many plumbers have come and gone, never being able to solve it and if quoted for a job the reason doesn't add up to why it only happens randomly and in winter, we will have to see if it has to with our stack, we have asked the plumbers but they have always ruled it out.

Is the smell toxic? We have an infant in the home now which has us hoping for a solution ASAP
We are just ready to move at this point

Hello Jen,

When the smell only comes from one seldom used drain, it is probably simply a dry drain. You can just add water regularly, or pour a little bit of mineral oil into the drain – it will sit on top of the water and prevent the evaporation. More information here:


Jeanne Vogel on November 14, 2016 14:29

Thanks Jon. Our cottage in northern WI is about 4 years old and very heavily insulated (as you talked about) I notice the sewer gas problem the most when we use a lot of hot water. (Tub, shower, laundry). I tried insulating the pipe in the attic with a neoprene insulation wrap and we still had the problem. Once we even heard the ice let loose and crash down. We are having a hard time finding someone to help us with this problem. The man who inspected/pumped our septic said he'd see what he could do. I will share this with him. Thanks again.

Hello Jeanne,
Ice breaking loose and crashing right through the basement stack elbow is a problem, see the Artic Ice web site and how they trap that ice.
Some of these entries that suggest suspending a pipe inside the stack seem to help solve that problem.

Rob on November 08, 2016 23:36

Thanks Jon I will give the mineral oil a try this winter and see if it helps also may try the dranger. I have been experiencing vent stack problems for a few years and was told by my handyman that it may be caused by the new windows, shingles and vent stacks that were installed.

David on November 08, 2016 07:14

I have resorted to enlarging the stack to 4" for six feet down into the attic and connecting with the 2" pipe there. If that doesn't work I'll start adding insulation inside. Let you know what happened by next spring!

Secondcost on November 07, 2016 21:27

I live way up north in Nunavut and work for the housing corporation. So I have seen this issue for years. We have had some success by installing a copper tee in a few of the plumbing vents, the branch of the copper tee is about 2 to 3 foot long and extends down into the vent, while the run of the copper tee is fitted with 4" long pieces of copper to prevent the tee from falling down into the vent. Also, the secret to eliminate this problem, from my experience with the issue, would be to devise a method to precipitate all of the moisture out of the air inside the vent, so that only the passage of dry air takes place at the entrance to the vent on the roof.

Hello Wayne,
Information from Winnipeg indicates that often the source of the ice in that micro climate is blowing wet snow, not so much moisture from the plumbing.

ken Turnbull on October 06, 2016 20:40

We live in southern Manitoba and experience ice capping every year and the only remedy is to climb up on the roof and pour hot water down the vent. I am absolutely amazed that their is no cheap fix reading that so many people have the problem. I also have been trying to think of something sprayed on the inside of the vent that would prevent the icing. Does the spray grease work?

Hello Ken,

Way down in this blog you will see several people suggesting grease and it seems to work. I would try thick white lithium grease that won't freeze. The other element that seems to help a great deal is to cut the 3" pipe in the attic shortly before it exists the room and put a 3" to 4" adapter, then exit with a 4" pipe. It is much harder to ice over. Don't worry about rain because the whole piping system drains. The only problem might be with birds nests and trying to put a screen cap will just freeze.

David on September 01, 2016 12:23

We've had the ice cap problem periodically over the last few years - I think it started after the installation of a second shower but can't be sure that's the reason. It's not constant and seems to be associated with very cold temperatures and (possibly) high winds. I have tried various greases and I think that may be helping but will likely try more insulation in the attic next. I've heard it suggested replacing the uncovered stack with wider pipe (4") may be helpful. What do you think?

Hello David,
Yes, the 4" section is highly recommended -- I have added some detail on this in the article above.
-- Jon

Christine on February 29, 2016 01:51

I bought an ArcticVent at the end of the summer, but because I live in a rural village in the Northwest Territories, I wasn't able to find a contractor willing to install the thing before winter hit again. Last year my husband was up on our roof every two weeks, we had to keep a borrowed 3 storey scaffold to get onto our roof but weren't able to borrow one again this year. We have been suffering with the sewage smell since November and I am afraid of how toxic it is! Here's hoping I get the ArcticVent in there this summer as I am never going through another winter of this.

Hélène Mercier on February 21, 2016 23:34

We just spent our first winter in our brand new house. Sure enough the vent did get a blockage ( got dry traps, gurgle sounds from the shower and tub, water in the toilet going down,..). Part of our problem I think is the fact that we have a very big attic and the vent is 10 feet high inside of the attic allowing a lot of cooling time. It was not insulated in the first place. The electrician just finished installing a heating cable with a switch. Within 24 hours of turning it on, we were back to normal.
I was considering putting some insulation around the pipe as well but will read the specs about that specific heating cable.

Michael Mazur on February 15, 2016 09:25

For the first time this year we have experienced the ice cap forming on the bathroom vent due to the extreme temps that we have had in the recent days.
We usually have this occur
each year and have cleared
the vent with water. We recently installed a new metal roof and I am reluctant to traverse the metal shingles right now. I will try insulating the pipe inside the attic this summer and see how this works

Denise on January 15, 2016 22:50

I put boiling water down the stack bur as soon as it gets cold again the smell comes back and the stack is froze up again is there any thing else I could do to stop the freezing

Keith Voykin on January 03, 2016 16:35

Have the same problem in BC Canada, for the last 2 years. Have rigged up a system using my snow rake poles and adding a drop pole (8"-12") wrapped and secured with old rag/sock. I sprayed a lubricant Moovit to saturate the cloth. Find that if this is done December, late January that there is no ice cap build up. The lubricant is rated for extreme cold and heat conditions. Prevents hoar frost or ice build up on surfaces. Have dormers with steep roof and got tired of sliding towards the edge of the roof so built the rig so that it could be used from a comfortable and safe area.

Flash Sentry on December 03, 2015 02:17

Can a frosted-shut vent stack prevent water from flowing into the sewer? Last year, I saw a frost cap protruding from the vent, and the floor drain overflowed. This spontaneously resolved itself. The same thing appears to have happened again. The roof vent cap was redone the other year, as per code, with a PVC extension, after a roof job.

Hello Flash,
Ice could have gone down the vent and created a temporary blockage -- or the slow flow of water due to no ventilation air could have slowed things down enough to allow freezing on the way out of the house.

One year our 4 foot frost line in Montreal dropped to 8 feet deep because of little snow and extended cold. Slow moving water can freeze.

Bryan Hut on November 03, 2015 18:14

Typically I clear our 4" stack once every winter here in New Liskeard, Northern Ont. It extends a foot above the roof-line and is often buried with one or two feet of snow on top of it that doesn't seem to be problematic. The ice sublimes at the level of the roof. I'm thinking of wrapping it in 1/2" closed cell foam and slipping a wider diameter pipe over it this fall. Thanks for all your great info, Jon; I recall your TV show.

Rob K on October 16, 2015 23:26

The pluming stack vent pipe seems to freeze in the attic in the winter the drains run slow and we get a sewer smell in the house until the spring thaw what do you suggest. I tried wrapping the pipe with pink fiberglass insulation but it not helping we have had new plumbing vents installed last summer which did not help either this seems to be worse these past few cold winters in Winnipeg as we have lived in the house for aprox 12 years. Would you suggest calling a plumber or an insulation contractor to help with this?
I enjoyed watching your show and pleased to read your web page.

Radapaw Ridge on October 01, 2015 10:53

Here's the same issue with a slight curve. We have a bad odour in our downstairs powder room starting in the winter last year shortly after the septic tank was pumped. Pouring a half a bucket of warm water seems to alleviate it but only until the temperature drops overnight and the odour returns in the morning. The curve is that it was absent all summer this year but returned in mid-September with the first dip in the outside temp. So is the "ice cap" problem a winter-only issue that requires subzero conditions or can this problem occur in the fall too? Don't want to pay to extend the stack if freezing is not the problem. Other causes?

Hi Radapaw,
Yes, Ice capping won't happen unless it is very cold out. If you have the problem in September, it is something else.
Check that your septic tank is properly vented and not creating pressure that comes back up the pipe.

Jeanne on September 28, 2015 00:40

We had sewer gas in our cottage on several occassions last winter. I especially noticed it after using a lot of hot water. (Baths, showers, dishwasher, etc.) Was told by a plumber it is probably due to the roof vent getting iced up. Thanks for the advice given in this article

Jerry on September 07, 2015 09:19

I put in a 3 inch cheater vent .Works great

Hi Jerry,
For everyone else, a cheater vent is a plumbing gadget installed inside the hose which allows air into the system when water is flowing. Some municipalities do not allow them because they are known to get stuck open by bugs and then you have unhealthy gasses in the house.
-- Jon

c winegarden on July 31, 2015 09:59

Same problem as the others at my cottage in Quebec. I have resorted to manually refilling the traps on the various sinks after flushing the toilet…when an ice cap has formed you can hear the traps getting sucked dry after a flush.

Ruth on July 08, 2015 13:21

We have a newly renovated older home and the new bathroom fans, when operating, draw a sewer odor into the house from behind the clothes washer (all on the same floor but there is a basement)..any suggestions? It is not a winter only issue.

Hello Ruth,
A clothes washer requires a standpipe, which is an open pipe that has a standard plumbing "P" trap on the bottom. The Clothes Dryer drain is simply hooked into this pipe with some open space at the top of the standpipe. If the Clothes Dryer drain is plumbed into the drain pipe with a sealed fitting, the large fast flow of water will empty any P trap and give you odours. By having the stand pipe open, it works as a siphon break and the P trap does not drain away at the end of the flow. No odours.
-- Jon

Don Timmins on March 24, 2015 12:13

In January the sink in the kitchen started to give a sound after the water drained. The sink is 20 feet from the 3 inch main drain. When the weather warmed up to 8 deg. one day the sound went away. I live in the Ottawa area.

Hello Don,
Yes, gurgling is a very common sound associated with Vent Stack ice capping. The water is flowing to the plumbing stack, sucking for air as it goes. If the vent stack can't provide that air, it draws air through the P trap under the sink -- hence the gurgle. If this is your only problem with ice capping, you could install a small vent valve on the drain line under the sink.
Look up Valve in the keywords, then look for the article "What is wrong with my gurgling double sink? The Vent Valve. -- Jon

John in Winnipeg on March 06, 2015 15:07

We have been in our house for 32 years and we never had a problem with the stack freezing up. In the summer of 2013, we had our roof re-shingled and the roofers replaced the stack where it exits the roof as it was level with the roof deck. Now we have a problem with the stack freezing up during the winter.

Last summer I insulated the stack in the attic as best I could (it is right against the inside wall), but that hasn't helped. I probably didn't use enough insulation. This summer I am planning on boxing in the stack and insulating it with spray foam/Styrofoam & fiberglass. We'll see how that helps & I'll let you know.

Currently, when the toilet is flushed, the bathtub drain gurgles and if I leave it for a few minutes I can smell the sewer gas. What we do after we flush the toilet is turn on the tap in the bathtub for a few seconds to refill the trap. At least that keeps the sewer gas from coming in.

Tom on March 01, 2015 13:01

We live in north Georgia. We moved in home in Dec.
plumbing ?
Our vent for septic was not extended thru roof but installed in front top level of home. We do get odors. How to solve odors & to conceal pipe!

Hello Tom,
If you mean Georgia, like in the southern states, you certainly do not have freezing problems. What you do need is to have the stack higher up on the roof where the wind will catch the gas and take it away. You can reroute the vent stack inside the attic, exit on the backside of the house right next to the top ridge. This way you could go up only about 6 inches and still catch the wind -- making the stack less visible.
-- Jon

Tom on February 26, 2015 17:51

I have a vent on the south side that doesn't ice up but the vent on the north side does. Could i tap into the vent on the south side so when the north freezes over the south side could take the odour away. In a sense tie it all in together?

Hello Tom,
I don't see a problem with that although you always want any horizontal piping in a vent system, in the house or in the attic, must drain back into the plumbing system. If it slopes the wrong way, or has sags in the line, any standing water will freeze and potentially close off your new by-pass pipe.
-- Jon

Bill Walters on February 24, 2015 14:39

ice camping in my van happens every year when the temperature goes below zero. I have found that running warm rather than hot showers; and letting bathwater cool before attempting ithelps to keep the vent pipe from getting as much steam and freezing up as quickly. wrapping a heating coil around the vent stack worked fine until sliding snow took both the heating oil and vent stack down with it. best advice would be to run as little hot water down the vents as possible.

Dianne Foster on February 23, 2015 09:44

Well last year I said I solved the problem with Ice Caps on my bathroom Stack by making the stack shorter , well this year 2015 I have had to go up again and pour water down it . only had to do this twice so far this yr much better than last year of doing it every 2 days , but it is still happening, so my question is how to insulate on the outside without putting an electric wire on it and going in my attic is not an option . should I clear the snow from roof vents also . we heat the house with a wood stove

Hello Dianne,
The easiest way to insulation a vent stack on the outside is to buy an insulated flashing. There is a hotlink in the article.
-- Jon

Mark on February 22, 2015 18:30

I live in Minnesota and used to have periodic problems with a frozen vent stack until my friend suggested taking a 1/2" diameter piece of PVC pipe (in my case about 9' long, but as long as you can make it before you run into your first elbow) with a PVC tee glued to one end of the pipe with short pieces of PVC pipe glued in each end of the tee to prevent it from falling down the vent stack. Drop this assembly down the stack (the tee prevents it from falling out of sight) and that's it. The warm air coming up the small pipe from inside the house keeps the vent stack from freezing over.

Hello Mark,
Now there's a creative solution, although I imagine it only works if there is no elbow inside the cold attic, allowing your pipe to get down to the heat of the house.

Mal on February 19, 2015 16:20

We need to poor boiling water down our stack (brand new house in Winnipeg) every few weeks or it freezes completely over. We are going to check the attic this spring to see if there is currently any insulation around the pipe or not. Thanks for the helpful article (one of the easiest to read and understand out there!)

Steve on February 16, 2015 15:45

I am not getting a sewer gas smell but the upstairs toilet is not flushing properly. I changed all the internal parts (water flow, flush valve and even the wax seal) to no avail. The toilet manual mentioned it could be a partially blocked vent. I went outside and I can see ice at the top of the vent. Can that be effecting a proper flush? It has been very cold here in Toronto

Hello Steve,
Yes that could be the cause. It all depends on your piping configuration, but if there is a long run to the vertical stack and a plugged vent pipe, even a toilet can be slowed down.
-- Jon

c m g on February 10, 2015 18:55

I'm having the same problem! Odor in the basement when someone takes a shower...
But now its February and I'm in western NY and we've had some MAJOR snowfall! My vent has got to be ice capped. Drains are draining slow! Especially the upstairs toilet and shower!

Marc on February 02, 2015 19:51

Vent stack blocks just North of Sudbury ON. Although it might be blocked most of the winter (if I don't climb to the roof to knock it off) the blockage and sewer smell is obvious when the downstairs' lift pump quickly evacuates the water and there is need for lots of air to fill that vaccum of air. This year i added about 12" of pipe; thinking I could get above the snow blowing over the peak of the house; as I've just read here, the length was likely not the cause. Thanks for posting this resource.

John Munster on January 26, 2015 16:54

Hello Jon,
Yes, I experience ice capping on my sewer vent several times every winter. I know the vent is frozen when it has been below -15°C for a couple days, and I start to get the sewer smell from the sink drains in the basement.
Luckily our bungalow's roof doesn't have much of a slope, so I can go up and unblock the frozen outlet of the sewer vent, easily chipping it out with a couple of pokes of a screwdriver. I installed insulation wrap on the sewer vent pipe in the attic, but it didn't help much. The outlet on the roof has still frozen twice this winter.
The pipe through the attic is 3", and the roof vent pipe is 4", so the outlet of the sewer vent pipe on the roof has a metal cap, which reduces the opening down to about 2". This 2" hole is where the freezing always occurs. I would like to remove this cap, but I can't, because of the 3" vent pipe ( in the attic) being loosely fit into the 4" roof vent stack. Removing this cap coould allow rain to flow down the inside of the 4" roof stack, and leak into the attic at the small (unsealed) gap where the 3" attic pipe fits into the 4" roof stack.
To make matters worse, the vent stack is on the north side of the house, so it doesn't really get any heat from the winter sun.
If you have any tips or suggestions, it would be appreciated.
Thank you for your attention, we listen to you on CJAD most Saturday mornings.

Hello John,
Change the joint between the 3" and 4" pipe for a real plumbing reducing fitting which will allow you to make a water tight joint. Now any water coming down from above will flow away. You still need a flashing around the roof penetration. Check out the insulated ones shown in the article above.
-- Jon

pauline on January 15, 2015 09:32

January 12th, 2015 I heard the gurgling and smelled the gas. I recalled that this was nothing urgent, but called my plumber. He reminded me about the ice. Sure enough i have about 6 inches of ice aroune/coming out of my stack. The other night i was out walking and noticed about 8 homes around my house with same ice on stack. I believe these homes were built in the 1940's or 50's. area is Felix and Spruce (west end) Winnipeg. Thanks for the good info

Carl Iverson on January 14, 2015 20:23

I'm having the same problem with the ice forming on the top of my vent when temps reach -15 for 2 or more days. In searching I found this solution at . Has anyone tried this? Do you think this would work? I just emailed the company and this was their response: Yes they really do work. I have testimonials on file, I can send you them as soon as my office personal show me how to send them to you. We have sent vents to northern minn. and to michigan, canada, new york , mass. conn. north dakota, and even to nebraska. we have at this point around 600 vents out and had great success. We have had a couple that had some issues of being to low on roof line to not get any sunlight to help thaw the ice out of them. But I did help with them on not frosting over as much. My cell number is 605-881-1419 please call if you have any concerns or questions. I will get you testimonials as soon as I figure out how to send them to you. Thank you for your time.

Hello Carl,
Thanks for the tip. I have checked it out -- and added it to this article for everyone to see.

michele on January 13, 2015 22:48

I am so glad I found your article on ice capping. last winter was quite severe in northern Ontario, and I lived with the rotten egg odor for much of the time. My house has a steep high roof, no attic, and I could never safely go up to pour hot water down the pipe. Plus the heavy snowload buried the top of the pipe anyway. This summer while having a new roof put on, I had both pipes extended another 3 feet up. I see now that this is not the solution to the problem.

Dragfluid on January 10, 2015 12:17

When I built our home 18 years ago, I thought that it would be a good idea to put a 180 deg cap on top of all the stacks. It just seemed to make sense. Never had any smell issues.
5 years ago, we had the roof replaced. Of course the roofer cut off the 180s and I didn't put any more back on. We started having ice cap issues in the below zero temps that we get in MN. for one reason of another, I never got around to putting any on before last winter and had been busy all summer with other projects.
Just finished putting the last 180 on this morning. Looking forward to no more stink!

Hello Dragfluid,
I have never heard of using "goose necks" on plumbing stacks anywhere. Let me know if it works this time.
- Jon

Ryan on January 07, 2015 18:04

I ran into ice clogging last winter and found a decent solution - it may prevent some broken legs. My roof is so steep I can barely walk on it in the summer. In the winter it is just out of the question. So I got two 8 foot 1x2s and screwed them together (with about a foot of overlap). That makes a 15 foot pole. At the end of the pole I taped a small plastic watering can. I can then fill the watering can with boiling water, stand on a ladder beside the house, and dump boiling water into the vent stack. Sometimes it takes a handful of times if it is really bad, but it gets the job done safely. Another thing I have done with this is tape another stick - maybe 18 inches - going off sideways by the watering can. I use that to stick down the vent pipe and feel if the clog is gone.

Variations on this setup would be a longer pole (I am not sure how much longer a person could handle, but maybe if you left some of the pole hanging below you, it would balance itself...). Or maybe for longer poles, you could screw or tape a stick off to the side as a support? That may interfere with pouring, but it could be something to explore. Maybe you'd need to tape it such that the pole still twists for pouring? Anyway, hope this helps someone.

Hello Ryan,
I'm for anything to keep people off the roof in the winter.

Garret on January 07, 2015 15:31

Our washer was moved from the bathroom to the back room. Is the pipe sitting on the bathroom floor uncovered creating the ice problem on my vent stack. also large ice dams on the east and west sides of the roof reach almost half way up the roof, i'd say a good 5' up the roof. on the edges of the roof the ice is about 5" high. Is this dangerous?

Hello Garret,
I doubt that a run of vent pipe inside the warm part of the house is a problem. But those Ice Dams on the roof sure are a big problem. Please look up "Ice Dams" on the search page for information about what causes this. You need some work done on the ventilation in your roof soffits.
-- Jon

Dick Lorenzen on December 31, 2014 16:36

Live in Northern Colorado, get some below zero temps and each time we get sewer smell in upstairs bathroom. Had plumber out-no issues found. Added larger diameter vent stack, still get smell.

Jim on December 26, 2014 15:38

I'm on the fourth floor of a condo in Sask. when this occurs we often find that running hot water in all the drains sends heat up the stack and melts some of the frost/snow buildup - make sense?

Hello Jim,
Enough hot air could work -- but on the other hand, often steam is the source of moisture for the ice. I guess it is a balance.
-- Jon

Ken on December 19, 2014 17:24

Living in Winnipeg for decades in the same home, never had this trouble until now. Had bad smell in bathroom from tub; went on roof to look and found ice capping. Will look into insulating stack next. Thank you.

Michaela Kraft on December 03, 2014 00:30

We are experiencing the odors in the bathroom sink and a slow toilet. We've also noticed some ice on the stack. How do I get rid of the ice without the trip up the snowy roof resulting in the broken leg you mentioned? We've noticed a sewer smell out in the street lately too. (Regina, SK)

Chris Marcello on October 26, 2014 11:22

The gasses that have been described are exactly what is coming from the basement. However, it happens throughout the whole year, and there are no gargling noises in any of the house sinks or tubs. In addition, the smell will disappear and come back a few days later with no apparent reason. All water traps in the basement are filled with water, and the smell seems to be coming from one 5" closed cap on the concrete floor, as well as a cap on the vent stack in the basemen. Both caps have been replaced, and a smoke test has been done, but one did not correct the smell and the other did not show any plumbing leaks. Does this mean I have to break the concrete floor to get to the problem? It is not a moisture smell, it is full blown sewer gasses that are getting into the house.

Hello Chris,
Before breaking up the basement floor, I would hire a plumber with a camera snake. He can give you an inch by inch recording of the whole drain line right out to the street. That way you know what is the problem and where it is located.
-- Jon

Keray on October 08, 2014 23:50

Hello, I have read the other comments found a few things to try but my question is I live in Alberta my acreage is only 6 years old I've talked to multiple plumbers and we can not figure out why I'm getting sewer gas in my basement! It only happens in the winter the vent stacks ice up occasionally but it seems to do it when they are clear as well I've put a check valve on my sump pump and changed vents on the roof from 3" to 4" we also run water regular down stairs in p traps so just wondering if you have any ideas to give a try? Thanks

Hello Keray,
Mentioning acreage makes me suspect you are not on a city sewer system but on a septic system. You may want to check your septic system to see that it is properly vented -- and that wind is not pressurizing the tank, sending odours back into the house.
-- Jon

Connie Monk on October 01, 2014 17:05

W don't have this problem in the winter that we know of but we are having issues right now with a horrendous odour coming from the stink pipe and flies all over it. Could there be a dead animal down there? Or do we have a bigger issue? If it's a dead animal what should we do?

Hello Connie,
I think you are probably right -- animals, birds etc do fall down plumbing stacks. If you can't "fish" them back up with some kind of a hook -- even a fishing line, then you will probably have to open the vent pipe in the attic. You might want to first ask a plumber with a camera snake to drop it down the pipe to actually "see" what it is and where it is located. That could greatly help with the extraction.
-- Jon

Eileen Findlay on September 14, 2014 15:24

We have an old two story home in River Heights. We've been there for over 10 years... had to have a brand new sewer line put in from the street to the house when the old one collapsed. What a disaster that was! We put in a brand new water line as well.
. From the beginning, we have had this awful problem of sewer gas smell wafting through the house. It is especially bad in the fall when temperatures start to drop and of course it stays through the winter as well. We have on rare occasions had it happen in summer...So..a plumber came out checked out everything and still couldn't fix the problem. It is so gross!! We have spent a lot of money fixing up the house but cannot have people over because of this smell!! Help!!

Hello Eileen,
In an old house, and it being this consistent, I would suspect it is a broken vent pipe hidden in the wall someplace. I would suggest that having a plumber pressurize the vent system with smoke might help you to locate the break and minimize the opening of walls.
-- Jon

JMK on July 22, 2014 18:38

Have smell 24-7 Cannot locate it! HELP!!! Roof vents seem clear. I have it in summer and winter.

Hello JMK,
Smells both summer and winter are not about vent stack ice capping. I would suggest that you have a missing trap someplace, or a dry trap, like in the basement floor, or a broken vent pipe hidden in the walls.
Put water in all your traps to see if it goes away. If that leads nowhere, I would suggest having a plumber pressurize your vent system with smoke to see where it might come out.
-- Jon

Lisa on July 17, 2014 01:47

We've never even come close to seeing snow or ice on our roof here in mild Marin County, California, but our house has a waxing and waning odor whose source we can't identify, and these posts have gotten me to thinking it simply MUST be the vent stack. We have been searching for 1.5 years as we have demolished and remodeled, spending an embarrassing amount of money and time (hardwood/paint/carpet/drywall/chimney/window replacement - all natural/low VOC); met many self-proclaimed experts (mold, HVAC, drain pros, etc. who have never even suggested the vent stack); and now I am begging our contractor to have a plumber thoroughly inspect our vent and line from the washing machine, though he is resisting. Any specific suggestions? Thank you!

Hello Lisa,
First, fill every drain in the house, including the clothes washer standpipe with a cup of water and see if the smell goes away. That can help to identify a dry drain. Don't forget any floor drains as well, especially if there is never any water going down them. Look up "Dranjer" on my search page.
-- Jon

Valerie on May 01, 2014 07:16

Jon, I only get the sewer smell when it rains, not in the winter. Any suggestions where to start looking for the problem? Thank you !

Hello Valerie,
Your Videotron e-mail tells me you are probably in Montreal and your problem tells me you probably have a "basin" roof where the rain drains down the middle of the roof into the sewage system. (Agatha Christe was my aunt.)
I would guess that re-roofing jobs in the past have partially filled the vent stack/roof drain with asphalt slopped into the drain - which causes the same lack of plumbing ventilation as an ice dam when it rains heavily. I would recommend having a roofer clean out the drain with steam, basically melting the asphalt and spreading it out further down the pipe, but eliminating a block in an elbow on the way.
-- Jon

Lambert Curzon on April 08, 2014 03:29

I live in the Yukon Terr., this is only the 2nd. winter since I built my house in 1985, stack is 24",roof is 7 / 12 pitch and over 42 ft. off the ground, often we have - 40 and colder, attic above second floor bathroom is above a cathedral ceiling, not too far from a double walled safety chimney that gives off heat, as the vents at each gable end of the house tend to ice up as well. No sewer gas smell, however flushing or running water upstairs causes gurgling noises in the downstairs bathroom. My stack is 4" with two 2" pipes pointed down at a 45 degree angle, and the ice blocks at the top. I plan to install a new pipe, 4" right at the roof with a increase to 6" and install a galvanized cone above the 6" ABS pipe as well as install 2 , 3 " pipes aimed down at a 45 degree angle. Will grease the galvanized cone inside and out with axle grease or something that should prevent snow from adhering to it. Will let you know in 2015 if it works.

Renata on April 05, 2014 11:54

Hi Jon...My husband and I have been dealing with the sewage smell coming from our downstairs bathroom. On closer investigation the smell actually is strongest at the light switch. We've never experienced the smell before and we live in Upstate NY where we've experienced a lot of minus degrees this year. I feel it's been the strongest since the winter set in but feel it may have started earlier. With the smell coming from an outlet is it also possible there is a crack in the stack somewhere? This bathroom was part of a new remodel in 2008.....but we've had not smell until 2013. We also have a steam shower in our master bathroom and I'm wondering if that could be contributing to the possible freezing stack?? I'd love to get your comments on this..Many Thanks Renata

Hello Renata,
Sewer smells coming out of walls is almost a open joint in the ventilation piping. Because this pipe does not carry water, it is all too easy for a plumber to forget to glue the joint between pipes and it never gets notices -- no water leak. But it can give a smell leak, especially if something has moved causing the joint to actually open up. Few video cameras can nagivate inside the 1-1/2" piping used for plumbing venting so about the only way to trace it without opening the walls first is to seal things off like with a plumber's drain piping pressure testing and force smoke into the line. If that produces smoke out your electrical outlet -- you know you are close to the open pipe. That at least reduces the renovation job.
-- Jon

Sonia on March 30, 2014 11:02

I don't have gas smells but my washing machine and bath tub will not drain fast enough,it comes back up through the washer drain pipe. Would this be caused from snow over the vent pipe? This is my first winter in this house and had the septic pumped before winter and didn't have a problem until we started getting a lot of snow. I had my roof shoveled off but did not seem to help the drain issue but there could have been snow in it that was over looked.

Hello Sonia,
Before spending money on trying to trace problems with the vent stack I would suggest that you have a plumber snake out the drain line from your washing machine, or at least open up and clean the trap at the bottom. All too often this is simply something that has come through the washing machine and is clogging the line.
-- Jon

Ruth on March 24, 2014 14:26

Are there sometimes separate vent stacks? We have no odor problem, but this winter, sometimes the drains in the bathroom sink and shower have drained very slowly, and other times they seem fine. Have used a drain cleaner but it doesn't seem to make a difference. Haven't noticed a problem with other drains in the house.

Hello Ruth,

Look on the roof. Are there two black pipes sticking out? Yes there are sometimes separate vent stacks. If the problem lasts after the snow is all melted off the roof - you need a plumber.

Mike on March 18, 2014 00:24

While I raked the snow off my roof this winter, I noticed an ice cap and pulled out a huge chunk of ice. But the next time I tried, the ice went down the stack. A few months later I heard a loud clunk, and knew that the ice went down farther. Then one evening, after taking a bath, my kitchen ceiling, two floors below, began leaking. I found out that the water backed up past the toilet wax sealing ring. I'm wondering if I can install a push up devise to pop out that ice cap?

Hello Mike,
Because the stack is inside the house, that ice should have simply melted away and is no longer there to block things. What most probably happened is that the falling ice block hit an elbow and broke it, or stressed the elbow and it broke later. I would recommend getting a plumber with a video camera take a look from the roof.

Linda on February 27, 2014 20:57

Have had a frozen stack several times before this year, however this is the first time we had the sewer smell associated with the loud gurgling in the tub when we flush the toilet.

Dianne Foster on February 16, 2014 18:15

I live in Northern Ontario and have solved the problem with ice caps on my bathroom vent causing a sewer smell in the house , Its been 2 weeks now and I have not had to go on the roof to pour boiling water down the vent . We cut the stack down to about 6-8 inches , that solved the problem . Our Plumber said our stack was to high and when the hot steam rose up by the time it reached the top it started forming an ice cap because it cooled down to fast , since we cut the stack down we have had no more problems (2 weeks now), we were going on the roof every 2 days , hope this helps some of you out there .

Hello Dianne,
A shorter can certainly help, with the limitation that it must stick up out of the accumulated snow. So if someone has a deep snow load on the roof, that may not be the solution for them.

Sharon C. on February 16, 2014 17:11

Appreciate all the sewer gas comments. - somewhat comforting to know others are experiencing this issue. Have had several bouts of sewer gas during this long cold Regina winter. Our sewer smell originates in our master ensuite - usually the sink but sometimes the shower drain. When the toilet is flushed, our washing machine drain gurgles. Curious why the gurgles don't happen when the other two toilets are flushed and there is no smell in those bathrooms (I I'm thankful - don't get me wrong! )

Hello Sharon,
Some houses have two vent stacks. You may have one that blocks and the other that doesn't.

W Secondcost on February 15, 2014 16:25

Here on Baffin Island Nunavut frozen plumbing vent stacks are a common occurrence. For environmental reasons, I don't like the idea of using
energy to solve this problem. However, a couple ideas i have been thinking about lately to solve this problem, which would not require the use of energy would be to either: 1) develop a method to precipitate the moisture out of the sewer gas before it has a chance to reach the exterior plumbing stack (where it usually freezes), or a simpler method might be 2) coating the inner(down about 6 inches), top rim and about 1/2" down the exterior
of the exterior plumbing stack pipe with some kind of compound that would not allow ice to adhere and build up.
Perhaps the compound could be waterproof grease, or similar in chemical composition to Rain X? I am not currently in a position that i can experiment, however, if anyone tests either of these hypothesis, please post your results to this forum. Thank You, Wayne S.

Hello Wayne,
Read below, grease has been suggested as working. I haven't tried it. Enlarging your vent from 3" to 4" just before it exists the roof seems to helping in the far north.

Dave on February 09, 2014 17:41

I bought insulation and headed up to my attic to insulate the vent stack only to find out, the stack drops down to the top of the insulation and then snakes around horizontally for about 20 feet in the cold of the attic. No easy way to insulate all this pipe. Would it be a waste to insulate the vertical rise? The frost could be building up anywhere. Does this meet Ontario code?

Hi Dave,
Yes insulate the vertical section, it will help. The plumbing code requires that all "horizontal" runs slant back to where they came from, to keep them drained of condensation. Most important is to have it properly supported so it creates no dips as they fill up and freeze quickly.

John in Minnesota on February 09, 2014 07:39

Our house is less than 10 years old. Its a very " tight" house with spray foam insulation. Every winter there are times when we have a sewer gas problem. Usually we just plug the drains for a short time. This cold winter of 2013-14 however the problem is really bad all of the time. There is nothing very unusual about our house. Can't believe more people don't have this problem.

Hello John,
Lots of people have this problem, and if you look at this blog, a lot of them live with you in the prairies.

Dianne Foster on February 08, 2014 21:08

we had our stack freezing up every 2 days with an icecap on it, our stack was about 1 1/2 high , our plumber said to cut it down to 6 in because it was to high and the warm air had to far to travel up the cold stack causing it to frost up with an icecap , we cut it down to 6 inches , so far so good been 4 days and no freeze up yet x my fingers this is going to work

Hello Dianne,
Cutting down a high stack can help, as long as it is tall enough to get through the snow that accumulates on your roof.

Ralph Christianson on February 08, 2014 19:49

I live in southern Manitoba, my stack freezes up quite often this winter due to our ever lasting cold part of the winter and so I have been pouring water down it about every other week. The other day I went out to do it again and I wrecked my knee so that ends that project for now. We have a number of birds in the house but the humidity is at 45% and this is enough to freeze up the stack in the low -20s and colder. My stack is several feet high so it would not get filled in with snow, so should it be shortened in the spring? .I have wrapped R12 around the pipe in the attic but that did not help. Too bad someone does not have a solar heater you could just set on the top of the stack that would keep it clear.

Hello Ralph,
All electrical devices you might want to use have the problem that they have to be certified as "explosion proof" because of the methane gas in the sewage system. The Artic Vent is about the only one I know of that is made specifically for this, but it is expensive.

Leo on February 01, 2014 19:27

My house is in Ithaca NY. When we have protracted spells of 0-10F weather, the vent pipe freezes over and we get the house smells. I'll look into the solutions mentioned here. Thanks!

Susan Filsner on January 29, 2014 19:02

I live in a 1930's cottage in Hudson Quebec. We just had a 2 week spell of -20+ temperatures and I woke up to the smell of garbage throughout my house. The night before the smell began I heard an odd noise coming from the pipes in the upstairs bathroom. My drains and toilets are not backing up. Would talking hot showers and doing hot laundry help as climbing on the roof is not an option?? Or, do I just have to wait for it to thaw??

Hello Susan,
Once it is blocked, steam won't do much good. You will need to look at some of the permanent remedies listed above as a summer project.

Canadian Problems on January 27, 2014 16:51

When it gets cold (usually below -20C) the top of my 3" vent pipe gets ice built up presumably from the steam freezing and a little snow getting in there. In the summer i am going to insulate the pipe in the attic and maybe upgrade to a 4" pipe.
As a temporary fix I thought of buying some kind of coating/gel that repels moisture, and rubbing/spraying it into the top of the the pipe where the ice builds up. I see Wayne Smith commented that grease will do the job, so thats what I will try. Thanks for the articles and comments, I will try and post the outcome.

Hello Jesse,
Let us know if the grease actually does any good.

Joanne on January 25, 2014 10:01

Having sewer odor here in the "Middle of the Mitten" aka Michigan. We have lived here for 15 years and at the beginning it didn't occur. It has occurred in other winters when the prolonged cold and snow blocked the vents on the roof. This January my husband has been up on the roof 3 times already and last summer he installed massive amounts of insulation up around the pipe vents in the attic/roof when we had it reshingled. Now I've finally called a plumber for an opinion as I can't take the smell anymore. My husband has acclimated to it I think or is just plain tired of going on the roof. (Can't blame him!) What a pain. He is an engineer and this is one problem that is just causing rancor; no pun intended in the household. (We can't do the electrical tape due to fire codes). Maybe the 3-4" pipe refitting solution? GRRR.

Hello Joanne,
It is expensive but the Artic Vent can solve the problem definitively as it is a heating system that will pass fire codes.

Dianne Foster on January 20, 2014 15:25

Kenora Ontario, This has been the worst year for ice blocking our bathroom stack on the roof , we have to go up every 2 days and pour boiling water down it , If we insulate the top portion of the stack on the roof would that help as we cannot get into the attic .Getting frustrated with this , we know when its blocked by the rotten egg smell.

Hello Dianne,
Enlarging the section of the pipe outside, and putting on an insulated flashing as you see in the article could help.

Paul on January 11, 2014 21:21

During our Southern Ontario 2013 Christmas cold snap our kitchen sink seemed blocked. After using a plunger, a snake, and a bottle of Liquid Plumber to no avail, we concluded that the vent could be blocked. Yes, it was crowned by an ice cap!
This vent comes through a cathedral ceiling, so there is no attic access and most of the common remedies can't be used, except for a heating cable.
Meanwhile, we patiently wait for the sink to take its time draining each time, and for the weather to warm up. Luckily, no sewer gas is escaping.

Lisa on January 10, 2014 20:48

Thanks for the info. I thought I had nixed my ventilation problem this summer when I extended the outside pipe to avoid snow getting into it and causing an ice damn (which happened last winter)...but just read here that all I have done is increase the area for steam to freeze -so I may have made it worse. The stench is back & I keep pouring water in to the laundry drain. Seems to empty (gurgles) every time the toilet is flushed. We have just been through an extended cold snap but tomorrow is going up to +7 C. Hopefully a couple of hot showers will help melt it.

Jack McConnell on January 07, 2014 19:24

I came home and my family was complaining of sewer smell. It happens only in the winter most every year so I know it had something to do with cold weather in Michigan. after reading some blogs this afternoon I went outside and took some pictures of my vent pipe on the roof. i blew the photo up on my PC and sure enough the 3 inch vent has snow on top of it, meaning it is blocked. It is 0 degrees out, not sure how I'm going to resolve the issue yet. Suggestions are welkum.

John Weidner on January 06, 2014 21:08

I hope you welcome posts from the great state of Wisconsin. We are having 16 below temps with wind chills hitting 45 below zero. With that being said, we are starting to get gurgling in our sinks after we flush the toilet. I braved the cold and fear of falling off the roof and from what I can tell there is no ice cap or obstruction in the vent pipe. However, in my attic I have two vent pipes from the bathroom and laundry tub leading to the pipe coming out of the roof. I can't see inside the 'T' before it goes out the roof. Will this problem go away when it warms up in a few days or do I need to pull the trigger on a plumber? Any help would be appreciated. Love your website!

Hi John, those horizontal pipes in the attic could be iced up -- they are supposed to slope back to where they came from to prevent that, but with poor support they get dips in them that fill up with condensation, then ice. Yes thawing will solve the problem.

Deborah on January 04, 2014 19:59

this winter of 2013-14, only when wind chill factors are high is there a problem here with this stack - usually get a neighbor to come, climb the ladder for me while I secure the ladder - then he takes an 8' piece of 2x2 to knock off the ice capping -that will last until the next high wind chill..........pretty much live with the problem when really cold - speaking of spending the winter with a broken leg - yeah I know all about that one!.........cannot find one of those thermostatically controlled tapes.....have called around to no least it only occurs during the winter - so far!

Michael Faber on January 04, 2014 08:52

I have been having Sewer smell problems during really cold spells for a couple years now since I bought our house. Thanks to the information I found here and elsewhere, I went on the roof and discovered a mostly blocked vent pipe from condensation freezing. I poured hot water down it and the fumes inside the house disappeared. Now I need to determine how to solve it long term and am looking into some insulating options. I want to see if its possible to get some foam insulation similar to what is used for hot water pipes but just larger to accommodate a 3 inch plastic vent pipe.

BB on December 18, 2013 16:39

We have been experiencing the odour for the past week. The winter of 2013/2014 has been very cold in Manitoba. Are there any companies that will crawl onto the icy roof and clear the stack?

Hello BB,
There are companies that clear snow off roofs, so they could do the job. Just be sure they carry insurance so you are not stuck with a medical bill if a workman falls. Unfortunately, must jobbers who offer to clear snow off a roof have no insurance.

Pat on December 17, 2013 11:18

Our sewer pipe for the gas comes out the side of the house, does go up and just comes out of a 3 inch pipe and about 8 or 9 inches away from the house and is freezing at the end. How can we stop that?

Hello Pat,
With a sewer pipe that accessible, just pour hot water down to clear it. But plumbing ventilation stacks should never be that low because those nasty gases could go up and into a window. That is why they always go out through the roof.

Adam on December 16, 2013 21:47

I wish i would of read this years ago. I live in Northern Ohio and it gets down to the single digits often in the winter hear. Especially this year. Smell always occurs in the winter. Im going up on the roof tomorrow to see about the ice capping. Hopefully i don't fall (snow will cushion the blow i'm sure :) I wonder if putting a tee on the end would help?

Hello Adam,
As a matter of fact, some kind of wind shield for the stack could help -- especially in windy areas.

Jon on December 13, 2013 13:35

Lyndsay -- sewer odours are never healthy, but not as bad as physical contact with sewage back-up water. Yes live with it for the winter, but you should consider doing something in the spring for next year.

Lyndsay on December 12, 2013 21:38

I am also experiencing this awful smell.... But I don't think it's even an option for me to get up to my roof. If I just leave it and let it thaw by itself is it in any way dangerous? Or just stinky?

Jon on March 22, 2013 12:32

In the middle of December the coming and going of the smell is almost always related to vent stack blockage -- see that section above.

Wendy on December 16, 2012 23:12

OUr house is 4 years old. It smells like a sewer every couple of days from our master suite, 3rd floor lasts for a couple of days, then goes away for a couple of days and comes back. What could be causing this???

Jon on October 21, 2012 12:20

Washing machines pump a lot of water out quickly and that can create a siphon in the line that pulls the water out of the trap on the washing machine line. That is why washing machine drains are always looped up over a tall stand-pipe (higher than the water line of the machine) which has a trap at the bottom. This assures that lots of air can slide in as the water is being forced away -- and prevent ending up with a dry trap.

Matt on March 22, 2012 10:09

Smoke test the sewer vent system -

Geoff Clarke on January 11, 2012 13:57

We are getting the sewer odors (we have a septic system in the backyard)every time we do a wash(laundry)summer or winter. It is very strong in the basement and don't know what do to about it. Do you have any suggestions?

Dave of Calgary, AB. on January 20, 2011 01:33

We are having this Ice Blockage of the Vent stack problem presently in our house in Calgary. This is the worst it has ever become because of the long cold weather.I will be adding an Insulation Wrap of R12 around the Plastic Pipe in the Attic. Thanks for your web site and all of the help full hints.

Clinton on December 17, 2010 17:49

Here is my temporary solution till the outdoor temperature warms up. Since the odors emanate from my bathtub, I (a) open the windows after a shower to vent the bathroom, (b) plug the drain with a stopper, and then (c) leave a little water in the tub. This acts as seal to prevent the odors.

Jon on December 15, 2010 20:20

Hello Mike, Hot steam in the right outdoor conditions might open it up but in very cold conditions would just add more ice. As for that wire you want to put up there, when I began to research that option I ran into the problem that none of the common de-icing cables made for roofs are "explosion proof" and there is usually methane gas in the plumbing stack. Boom! Steep roofs tend to have more problems because the stack is often sticking out in the cold higher to get up and away from the roof in a horizontal measurement. More exposure, colder stack. This is where the Artic Vent would be a real solution.

Mike S. on December 13, 2010 17:47

I have an older house in Western Manitoba. Every Winter the vent stack frosts up, and a lovely rotten egg smell develops in the basement. It's happening right now...arrrr. Problem is my roof is very high, and very steep, so jumping up there and pouring hot water down is out of the question. I need to create some kind of 'remote control heat ring' that sits on top of the stack... so when it frosts up i go outside, hit a button, and the ring heats up for an hour, removing the frost. Do you think running a hot shower for a while will help to remove the frost? or help it just get thicker. Cheers, Frozen & smelly

Brian Tanner on December 11, 2010 12:02

We purchased a home in Winnipeg (70s construction) and now that it's cold we are having this problem. My father in law thinks it's ice capping. I will post a follow up here when I determine exactly what the issue is. Thanks for this tip page by the way, the main text and the comments are extremely helpful.

Wayne S. Smith on November 17, 2010 09:43

I have seen the smell problem show up in some new homes. As a builder and responsible for some large scale renovations, all work has to be inspected. In the case of a new home where everything was to code, the inside of the vent stack developed a thick layer of whore frost just at the roof line - possibly from infrequent use of the system. An electric solution would help to fix the problem but by spraying some grease down the inside of the pipe would stop the moisture build-up. As a builder I would go to the 4in vent stack. I do like the idea of an animal guard.

Bryan Lukie on November 02, 2010 17:52

I had this problem recurring in a new house built in 1975. It involved the basement floor drain, puzzling the builder and several plumbers who were consulted. It was finally solved by placing a fiberoptic camera in the main sewer line under the basement floor and watching the opening to the floor drain as the upstairs toilets were flushed. Water was seen flowing from the sewer line into the line from the floor drain (the pipe from the floor drain P-trap had been incorrectly installed, sloping upward from the bottom of the trap to the sewer line). I wonder how often this happens?

reg boulette on October 19, 2010 11:23

If you experience a blockage, don't over look the possibility of an animal falling down the vent pipe and dying at a piping junction. Happened to me. Now have 1/4 hardware cloth over the vent stack end.

Lewis Rogers on October 16, 2010 17:38

I only had ice clogging the vent stack once. After hours of snaking my drains I eventually smartened up and checked your web site. I cleared up the problem quickly once I knew the cause.As to the odor problem - my floor drain in the laundry room is right under the washing machine near the laundry tubs. I installed a permanent hose hookup to refill the floor trap whenever odors occur (manual to the faucet). I really appreciate your info & miss your tv program.

Roxanne Shortt on October 08, 2010 13:49

I worked at a body shop in Lloydminster for years. Every so often each year the vents would start to gurggle almost sounds like a sploosh or sloshing. Then it would smell like sewer so bad we had to open the front doors or periodicly head to the back shop or outside because it was very strong some days. The contractor who built the structure was back a few times to try to fix the problem but it never worked, I guess the owner just gave up asking because it is still going on after at least 12 years.

Add A Comment

I encourage you to help develop the topic of this page by sharing your advice/comments/wisdom/personal experience/etc on this specific subject through the form below. Although I have developed most of this site with the encyclopedic concept of research and verification of information—I cannot vouch for anything contained in the comments below, but I may pick up, develop and include ideas put forward here into the primary entries. Please sign your name so we know who to give credit to. Your picture will show up next to your comment, here and elsewhere, if you sign up with Gravatar - jon

Please note that comments now need to be approved before appearing on the site to combat spam problems.
Sorry for the delay!