Re: Open Cell Foam Spray-up insulation under roof decking
Is that truly a fact? My attic was completely unvented for 86 years. The current roof is 8 years old and the shingles look fine to me.
Originally Posted by pjdaoust
Venting attics didn't become popular until after WWII. Actually it's hard to pinpoint when the practice started. It probably began at the same time we started insulating attics.
So are modern shingles just inferior to shingles from before 1945??? Possibly.
You also have to consider how hot even a vented attic is and how little actual airflow there is compared to the solar heat gain on a roof. Plus you have wood sheathing under the shingles. Hardly a good heat transfer material. The numbers I've seen say that the cooling effect is around 5F.
Shingles still curl on well vented attics. I think it has more to do with quality of materials. That's my take.
1925 Two-Story Stucco Beaux Arts Neoclassical