我应该密封爬行空间通风口吗？
我最近在我们的房子里完成了一个单人间的补充。它位于一个4'块壁爬行空间的顶部，其地板在一端的楼层位于另一端约18英寸。我放下了60万个poly，将墙壁延伸到大约一英尺，然后密封到混凝土块上。我用R-30板块将加法地板的底面绝缘。我还在周围的粉底通风孔中放入了大约15英尺的间隔。
I’ve read a lot on GBA about how bad vented crawl spaces are. The correct way to do them, as I understand, is to seal them, insulate them, and condition them with just a bit of air from the house HVAC system.
However, I’m wondering, given my situation, what would happen if I just sealed off the crawl space and didn’t insulate it or condition it? I understand that’s not the ideal, but wouldn’t that be better than leaving the vents open? If no moisture is getting through from the ground (due to the plastic vapor barrier) and no hot moist air is coming through the walls, what sort of problems would I be likely to encounter by doing this? (the crawl space also tends to stay very dry even if there’s a lot of rain.)
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Timothy,
You didn't tell us where you live. Climate matters.
Q. "I'm wondering, given my situation, what would happen if I just sealed off the crawl space and didn't insulate it or condition it?"
A. The only way to tell for sure is to experiment and monitor the situation. There is a big risk to this approach, however. You might monitor the crawl space for one year and conclude that everything is just fine. If you don't inspect it regularly, however, you could end up with lots of mold in 5 years. Monitoring means monitoring -- with your eyes, with a strong source of light, and with a moisture meter. You can't guess, and you can't stop monitoring.
If you sell the house, the new homeowner needs to get up to speed with your monitoring protocol.
It would be safer to follow the usual recommendations for sealed crawl spaces. That means that you need to insulate the crawl space walls. It also means that you need to provide a little bit of air flow.
I sympathize with homeowners who want to seal up their crawl space and see if it works without any conditioning. (This approach saves energy.) In some climates, and at some sites, a crawl space can be just fine without any fans or registers or air exchange. But you really have to monitor the situation regularly to be sure you know what is going on down there.
More information here:Building an Unvented Crawl Space.
Thanks for the response, Martin. My location is Harrisonburg, VA. We definitely get some hot, humid weather here in the summer. You are exactly right about my reason for not conditioning the crawl space from the start. I figured it's cubic footage to be almost 30% of the total cubic footage of the addition, so I thought I'd try to save a little energy by isolating it from the conditioned space. I'll keep a close watch on it and see how things progress.