Follow-up to Spencer Burnfield’s question of 13 March: Closed vs. Vented Crawls in the Pacific Northwest.
I’m still conflicted about closed crawls in the Zone 4 Marine climate of the PNW. Studies done by Washington State U. have shown that vented crawls “work” in this climate: i.e., they don’t cause the problems they cause elsewhere. Also, closed crawls allegedly exact a small energy penalty. Several local building experts have thumbed their noses at the East Coast “fad” for closed crawls. “The more vents the better,” one says.
To me, though, something doesn’t “work” just because it isn’t quite as bad as it is in other climates. I still don’t see the point of open crawlspaces. Why would you open this area right below your feet to outside air and insect infiltration just so you can stuff the floor joists with insulation that isn’t easily air-sealed? If closed crawls are so awful, then why do we allow closed basements to be built?
In our case, we’re building an 1800 s.f. house–on one story because my wife has Parkinson’s. 1800 s.f. is a lot more than the 500 s.f. or so of rigid foam that I would use on the walls and at the rim joist. As for the continuous air supply, I don’t see 5 min./hour (per J. Lstiburek) as a problem.
What do others think? I know Martin Holladay thinks crawlspaces are stupid, and of course he’s right. But that’s what they build around here. Anyone?
Last, forgive me. I must ask the toughest, most inscrutable question in Green Building. How does Joe Lstiburek pronounce his last name?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part