Jon Eakes

Last Updated: , Created: Thursday, December 13th, 2001

Soffit vents covered up or just not working.

Manuel from Kingston, Ontario has just purchased a house and knows that there have been past problems with ice-damming. He inspected the attic and found that there were enough roof top vents, but the old wooden soffits have been covered up with aluminium and there were no vents installed. How can he vent his soffits without ripping off the new aluminium? 

If the aluminium has a grill look to it, it may be ventilated. Go into the attic and see if you can see any in the soffit area. If it is smooth aluminium, you could cut holes through both the aluminium and the wood and install bug screens. You can actually purchase these soffit grills in both rectangular and round formats.

Continuous venting

Today almost all soffits have continuous venting with slots or perforations all along -- but all soffit vents are not equal and installation can make them work -- or not work.

By using aluminum for the soffit covering the material is rigid enough to not require any plywood or other backing – avoiding blocking the vent holes.  As you compare one style of perforated aluminum soffit covering to another, check the box or manufacturer literature to see what is the real “free ventilation” available.  Some have twice the actual ventilation than others.

There is a tendency to choose ones that don’t look open – just a cleaner looking wall to roof junction.  But when they are installed correctly, they almost all don’t look “open”.  The problem comes from a mis-conception as to how the wind reacts with the soffit grills.

People who want maximum ventilation will turn the grills so that the opening is facing the street – thinking that the wind will blow directly in.  Actually the wind hits the much larger wall and flows upward towards the soffits so much so that at the soffit itself, the wind is flowing across the soffit towards the street – against the wind direction!  When you install soffit grills with the opening facing the house wall, it actually scoops up the wind – and at the same time hides the openings giving a clean look to the wall roof junction. 

Moral:  Choose the soffit covering that gives maximum ventilation and place it so that you don’t notice those large open grills. 

Keywords: Ventilation, Condensation, Attic, Soffit, Air Flow

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