Quote:
Originally Posted by RodFarlee  Attic ventilation should be improved if the attic temperature is more than about 20 F higher than the outside air temperature. Such high temperatures as that (160 F!) will substantially shorten the life of asphalt roofing and plywood roof sheathing.
Homes built before modern building codes mandated adequate attic ventilation can benefit. It is relatively easy to accomplish in a variety of ways. Convective cooling using ridge vents, added soffett vents, even a cupola or wind turbine vent will in nearly all cases keep the attic temperature no more than 20 F above the outside air temp. In particularly difficult cases, thermostated, powered exhaust fan vents may be needed. The effort is quickly recouped in lower air conditioning costs. |
If the attic ventilation is passive, then other than convective currents, it takes a breeze to make the ventilation work. I have been in attics that were at code (our code, 1 sq. ft. vent to 300 sq. ft. attic, 1/2 intake, 1/2 exhaust) and even in washington it sweltering hot. The only other option would be to use active ventilation. In our area that is mostly wired for humidity, not tempurature.
When I replace my roof, I went with a ridge vent, and that helped.