Fastening to concrete or masonry? We've got three problems: choosing the right fastener, choosing the right tool and then doing it right. Here is some product information and trouble shooting tips.
Power Actuated nailing
Explosive shot nailling is the most common but the weakest of the serious concrete fasteners. They have some pull-out strength but mostly light and rapid fastening and good for preventing sliding of materials like the sole plate of walls.
There is a lot of tool competition in this field. Just looking at the Ramset line -- you can get the handyman hammer actuated (HD-22) or the more convenient trigger actuated (RS-22) which load one 22 caliber shot at a time. Then there are the semi-automatic models. The strip loaded SA-270 works exactly like the single load models but advances a strip of 27 caliber charges through the tool. Biggest error here is workers often advance the strip without firing, then don't go back to recuperate the shot -- wasting charges. With all three of these guns you have to choose the nail and the force of the charge to match the hardness of your concrete and the depth of penetration you need: yellow, green, brown or grey.
In the old days the charge shot the nail out like a bullet -- high velocity guns that are no longer around. Today the charge drives a piston at a low velocity but the weight of the piston then drives the nail into the concrete -- lots safer and just as efficient.
Besides safety, the piston concept has allowed for a new development as seen in the Ramset D-60 guns. They use a rotating disk for the charges, no missed shots, no wasted charges. Better yet, the charge is always the same, you adjust the piston travel to set the power for the material and the nail, a quick and easy twist on the shaft.
So what goes wrong with these tools? Today you have to clean out between the charge and the piston, regularly, just like rifle maintenance. Don't clean and the piston gets into trouble. Shooting with too much charge and shooting without a nail puts undue stress on the tool as the piston mechanism tries to overreach its travel, quickly destroying the tool.
Self-Taping concrete screws
These have greater holding power than the power driven nails but are a lot more trouble to install.
You generally know them as TAPCON screws. The Philips head frustrates many contractors but does prevent twisting off the head. You may want to try the new Vermont American ICEbit -- a Cryogenicatally hardened Philips head with ribs to increase gripping power. They claim the highest camout torque and it worked really well for me.
A Canadian company, Perma-Grip Fasteners sells a concrete screw called TapGrip which has a Teflon like corrosion resistant coating that eases entry and, yes Canadians, a Robertson head. Because of the extra torque from the square Robertson, they start with #10 and you do have to go easy to avoid twist off but they are a pleasure to work with.
Primary error with both screws is not drilling precisely the right diameter hole. Half a mm, like the difference between 12mm and 1/2 inch is enough to loose significant strength or jam the screw. Use exactly the right drill bit and remember that as it wears out, it looses its diameter -- so if the screws are getting harder to drive, change the bit.
Expansion anchors that open on the end of the anchor, like RedHead's TRUBOLT give very good pull out resistance deep inside solid concrete. Don't use them on brick or concrete block, they apply point pressure that can fracture the masonry. Full sleeve expansion like RedHead's DYNABOLT gives less grip but is the right anchor for masonry.
The strongest of all the anchors, two part epoxy is put in the bottom of a drilled hole and any threaded bolt is pushed in with the epoxy flowing up around the threads, pushing the air ahead of it. Ramset's EPCon epoxy system has both full sized cartridges and mini guns.
Common errors are: not completely cleaning out the hole, use compressed air if necessary; drilling the wrong size hole, you must follow the manufacturer's spec chart. Failing to use the disposable mixing nozzle weakens the epoxy.
**Originally published as an article by Jon Eakes in Home Builder Magazine, the magazine of the Canadian Home Builder's Association.