Airtight walls, not airtight crawl
kevinjm4
| Posted in General Questions on
zone 4c. This may be a dumb question. Would it be pretty much pointless to tape the seams of your wall sheathing if your subfloor is not air tight and you have a vented crawl?
Thanks
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Replies
Not necessarily, and for two reasons:
1- leaking into the house and leaking into the walls aren’t necessarily the same thing. If you are trying to keep moisture out of your walls, you just need to air seal the top AND BOTTOM of the walls before putting drywall up. That’s pretty easy to do. Do it the same way you would for a top plate in an attic.
2- you might decide to encapsulate the crawl space in the future making the issue of crawlspace leakage moot. You’d still be ahead if you’d done a good job airsealing the walls though.
I would do all the usually steps to make the drywall airtight regardless of the crawlspace. In my view, better air sealing is always a good thing. Any little bit helps.
Bill
Air leaks need two paths for flow, one in and one out.
If your walls and roof don't leak, even with a leaky floor, you will get very little air leaks in the house.
Why not tape the subfloor? Or is it already finished?
yeah, already finished.
The subfloor could still be airsealed with spray foam from below. Or, depending on mechanicals, with a taped air barrier fastened to the bottom of the joists. This would also help to protect/retain batt insulation if the batts fill the cavities.
Is there a reason the crawl space is vented and not sealed/conditioned?