Seal crawlspace or leave alone?
This is regarding a newly built home. The standard around here (PNW) for whatever reason are vented crawl spaces. When I set out to build this house I got so much push back with the idea of a sealed crawlspace I caved and went vented. I was a new builder on a budget and I only had so much energy to go against the local practices.
So currently I have fiberglass batts in the cavities of a my subfloor along with the standard black plastic vapor barrier over a dirt and gravel crawl.
As it turns out I get a bit of seasonal water down there. I noticed it early on and went to the effort of adding drain-rock where the water would collect so at least it would be kept below the surface of the granular fill and not make its way above the vapor barrier. That strategy has worked. The crawl space looks great after a winter with no pooling water anywhere above the barrier.
My question is about doing a sealed retrofit. I plan to put down a heavier, continuous vapor barrier and bring it part way up the stem walls with tape. At that point I am wondering about the detailing around the rim joist. Should I remove the batt insulation around there and add foam? The insulators did a really great job down there with batts but I imagine its the air sealing around that is important? Correct?
The other question is whether this would be worth it at all? Vented crawl spaces in this zone 4C actually can look pretty good over time. This climate seems to be forgiving for them. I definitely want to put in the more robust and better sealed vapor barrier, just not sure if sealing the crawl also is worth the extra effort? I do like the idea of lowering the potential stack affect in the house. Seems like it could help with what little draft exists.
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