©2013 Green Building Advisor. From The Taunton Press, Inc., publisher of Fine Homebuilding Magazine.
I am just finishing up a home.The roof was installed about 1 year ago.
I have 6-8 inches of closed cell foam on the attic side of osb roof decking(unvented attic). The roofer used synthetic underlayment(grip rite shinglelayment) on top of the osb and then certaintweed landmark asphalt shingles on top of the underlayment.There are garage sections of my roof that do not have closed cell foam used and a more tradional vented attic.
The problem is my shingles are devolping sections of linear buckling(raised up about1 inch , my best guess) parrallel to the roof rafters and these extend about 10 feet parrell to the roof rafters(about 6 inches wide )as visible from the ground. I dont think the problem is with deformed osb , as the buckles can be easily pushed down.The buckles also seem much more visible in the hotter times of the year and day.This is only occuring in the main roof with closed cell foam on the underside of the osb.The foam from the attic side looks fine with no cracks or separation from rafters.
My questions are:
1) Will the shingles that are buckled up still perform.There must be some movement in the shigles with the heating thru the day and season and I would imagine at the very least I will have some nail attacment issues . I imagine there is some shigle movement as the buckles increse and resolve thru the day/season.Do i need to replace/redo the roof?
2) Why did this occur? Is it shingle installation( installer says its not an install problem).Is it the underlayment , perhaps heated by the closed cell foam application against the osb and then became deformed or malfunctioned( the underlayment company has a tech bullitin that says there product performs to 230F) . Is it a shingle defect ( the shingle company allows the used of unvented attics with there product).
So far I have had the shingle local rep out and he has passed it on to a company engineer and so far I have not heard back
Thanks for any insight or suggestions.