Should I vent an unconditioned roof?
Home Built: 1915
Climate Zone: Marine 4 (Seattle)
Unconditioned Attic, no ductwork
Roof Joists: 2×4
Reroofed: Not sure, maybe 20 years ago, asphalt shingles
Ceiling Joists: 2×4
Ceiling Type: Flat, no vaults.
Square Feet: 900
Existing Insulation: Cedar roof shingles thrown on top of fiberglass bat.
Venting at Eaves: None. Zero. Zip.
Venting on Roof: 4 black roof vents (galvanized steel?)
Future Insulation: R-49 or R-60 blown (cellulose or fiberglass)
Future Modification: Whole house fan. (Maybe?)
I intend to insulate my ceiling with either blown cellulose or fiberglass. Watched the advertisements for each and remain confused. Code in my region is R-49 but not sure if R-60 would be worth the extra cost as long as I’m already doing the job.
At present, I have mold growth on the topmost ridge at least. I haven’t thoroughly inspected the attic with a good light yet.
I was told I should add ventilation to the eaves (drill holes) and insulation baffles. But then I read this article: https://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-attic-venting
Now I’m wondering if roof was originally unvented (1915) and if the 4 roofing vents were a later addition during reroofing jobs.
I’m a little confused about which direction to head. If I add a whole house fan then I’d need attic venting. However, I could also stick a fan in front of an open window in the back of the house and open my front windows. There aren’t too many hot days during the summer up here. On the other hand, winters have the highest energy costs and least comfort. I will definitely air seal the ceiling to prevent humidity from reaching the attic through air leaks (not sure if I should add an actual vapor barrier but the article sounded like that was unnecessary.)
If I decide not to install a whole house fan should I add venting and baffles along the eaves (no soffits on house)?
Additionally, should I remove the four existing roof vents on the roof?
I almost wonder if venting a whole house fan out of a wall might be better in my climate zone than doing it the traditional way through the attic. If I lived in a hotter climate like the Sacramento Valley in CA I’d definitely want to evacuate the attic, but up here I’m not sure.
Thanks for any advice. And if there are too many questions, my primary question is: should I add venting along the eaves before blowing in R-49 insulation?
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