Re-sealing failing SIP roof panels
We have a 7 year old SIP panel over a timber-frame home. We have noticed for several years significant condensation of moisture to the point of dripping from light fixtures and ceiling fans located in the peaks during hot summer days. Roof is a stone-coated metal shingle panel over Grace Tru-flex underlayment.
After many attempts to define the problem from our contractor/roofer and the SIP company we finally brought in our own professional. The verdict is that the SIPs at the ridgelines were essentially not sealed. The result was heat flowing into the house on hot days and condensing on cool metal surfaces such as the light and fan boxes, all of which are completely rusted from the inside.
In addition, after removing the ridge peak shingles, we learned that the opposite was happening in the wintertime. That is, the warm air from inside the house was flowing out and because the moisture does not penetrate the underlayment it condenses on the 2 x 24″ metal straps over the OSB outer skins and all fasteners and has rusted them all and also rotted the OSB in many spots.
The remedy will involve removing all rotted OSB and allowing any areas that remain wet to dry out completely and replace the OSB. In addition the recommendation is to remove 1.5″ of OSB at the peak and cut the foam vertically down to the inner-skin OSB and allow that to dry as well.
Once this is complete it must be re-sealed appropriately(?) and an entirely new roof replaced in the form of a fully vented system and using a moisture permeable underlayment. The current suggestion is some kind of caulk sealant that will remain flexible and then professional spray foam above that to the top.
Keep in mind this will be 3″ wide by about 13″ tall once the gap is opened as recommended. I have read many online opinions that stress a “belt and suspenders” approach to sealing SIP ridgelines in the first place (which didn’t happen at all) so my question is: Is the proposed solution the best option?
And if so, what exactly do we use and how exactly do we ensure that this will be the proper long-term solution, both for the sealing job and the possible replacement of the entire shingle/roof system?