Managing Attic Conditions Without Venting
Hipped roof with dormer roof replacement – conditioned attic, no venting
Hello GBA community. Doing a simple pyramid hipped roof with dormer replacement on a very old house in Grand Rapids, MI. Looks like 5A climate zone. There is no venting of any kind in attic. Roofer (trusted, experienced trade but not necessarily focused on green building) advises that there is not a reasonable and cost effective way to introduce venting (other reputable trades advised similar) and is advising conditioned attic with closed cell foam insulation under the roof deck to be completed later. He says this will help keep it cooler and create a moisture barrier for the deck. The significant cost (he estimated 5-6k) would mean we have to wait a bit to do the closed cell. Currently roof is insulated with old batt insulation with paneling covering it. I asked about shingle color and reflective granules as a way to keep it cooler. Roofer has advised Malarkey Vista shingles. Looks like Silverwood color is the lightest available, more grey than white I believe. Looking for advice on best way to keep the attic as cool as possible without venting and manage the insulation part of the project. I do not have a lot of experience with this sort of project. Any help would be appreciated. Thank you.
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Replies
You should have an insulation contractor give you an estimate at least, the roofer will not know price and insulators estimates are free
Edit, also read this: https://www.greenbuildingadvisor.com/article/five-cathedral-ceilings-that-work
Thank you very much, I will look at the linked article.
NWDeidrich,
There are now a number of ridge vents designed for hip roofs. If is feasible to introduce soffit vents, one of them may be a solution.
https://www.airvent.com/index.php/ventilation-resources/literature-sales-tools/hip-ridge-vent/14-hip-ridge-vent/file
If that isn't possible, assemblies #3, #4 and #5 in the link Freyr-design posted are probably your best options. #3 yields the best performing roof, but involves a lot of exterior work, which may be prohibitively expensive.
Thank you very much for the advice. I appreciate it.