Roof vents

[ScottAR]

Venting's main purpose is for shingled roof protection. In winter, under the snow, a warm roof will melt the snow till it runs down to the eve, where it refreezes. After awhile the water/ice will back up under the shingles causing damage. This is known as an Ice dam. In summer, the sun can overheat the roofing and shorten the life of the roof.

Walls are under the roof and no snow lands on those... /forums/images/graemlins/wink.gif

 

[boustany]

Absolutely right on the roof vent function.

Wall do need to be vented sort of. The ultraefficient houses that were build up here had sealed walls. During renos of some of them they open up the walls and find them completely full of mold.

So, apparently they recommend to drill the odd hole in the walls of these houses (only these special ones) and place a little vent in it.