Roof/Attic Ventilation - June 4th 2002



Question from Gord in Yellow Grass, SASK -----

Dear Shell,

I have a 1961 bungalow with a cottage style roof. It is insulated right out to the end of the eave. I had soffit and facia installed. I asked the installer to cut some openings in the ply- wood eave to help the attic breath. It previously had only a couple of small register vents and a couple of roof vents. Since this work was done, on cold, calm winter days the ceiling is condensating along the top of the walls inside the house. I tried turbines on the roof but on cold days the ceiling still sweats. I know you are very busy, but please contact me. If this continues, it will be expensive to replace dry wall and paint. Should I cover the holes made by the contractor under the soffit (which is backward to conventional thinking or does the roof need more ventilation? No contractor has been able to answer this; I really hope you can help.

Thank you,

Gord

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Dear Gord,

Roof cavities should be vented using a formula of 1 square foot (144 square inches) for every 200 square feet of attic area. 50% of the venting should be on the roof preferably through ridge venting and the other 50% of the venting should occur through the soffit. Your insulation should stop at the outer side of the upper outside wall plate (not to the back side of facia). Your minimum insulation should be R40 (12Ēthick) with insulation stops between the trusses or rafters.

Itís Just That Easy

Shell Busey