Crawlspace Insulation; getting conflicting information
I recently bought a 1974 single story ranch house in the northern front range of Colorado. After insulating and air sealing in the attic I’m turning my attention to the crawlspace that is vented to the outside. There is a a robust vapor barrier in place already. My furnace, ductwork, and plumbing are all in the crawlspace.
我昨天与承包商与承包商发表谈话，谁坚持认为我在螺栓内部使用的绝缘应该是蒸气打开的（矿棉或玻璃纤维布兰克特）。他认为，如果混凝土（无潮湿）不能干燥到内部，它可能导致将水分转移到框架上。我的理解是，绝缘应该是蒸汽关闭（Polyiso），以便温暖，潮湿的内部空气在冷基础墙上不会凝结。
I’d appreciate any thoughts..thanks!
Replies
Hi Micah -
1. Is the portion of your crawlspace foundation above-grade without any moisture protection and absorbing bulk water? If so, you need to move that load off of the foundation and/or apply a moisture-resistant coating of some sort. You can paint the concrete.
2. If your concrete crawlspace wall can dry to the exterior, then it does not matter whether or not your interior insulation is vapor permeable. More important that the unvented crawlspace has a continuous air control layer at the perimeter, particularly up in the rim joist assembly.
That's helpful, thanks!
Micah,
Have you read Martin's article on crawl spaces (//m.etiketa4.com/article/building-an-unvented-crawl-space)?
I think the biggest concern would be at the sill plate. Can you tell if there is a capillary break?
I suspect the experts will suggest that your contractor is misinformed.
你提到的蒸汽屏障在哪里？这听起来像是在爬行空间中，但它也会上墙吗？如果确实如此，混凝土已经密封从向内烘干。混凝土不需要干燥，永远湿润是湿润的。您的承包商对“上升潮湿”在轮辋托梁区域中的框架中的可能性是正确的。确保您有毛细管打破（塑料或金属）。如果你这样做，你们都设置了，可以在没有问题的情况下用泡沫塑料隔离。如果您没有毛细管休息，否则您可能想要添加一个，除非您的墙壁暴露在外面。
Personally, I think having the capillary break in place is the safest option.
Bill
Using 3" of reclaimed polyiso on the walls that stops a foot from the floor would allow ample drying toward the interior, even if there isn't much above grade exposure. Taping the cut bottom edge of the polyiso and installing 3.5" rock wool in that bottom foot would deliver the code-min R15.
Used foam is dirt cheap (usually much cheaper than batts, WAY cheaper than rigid rock wool) and fairly avaiable in your area:
https://boulder.craigslist.org/search/sss?query=rigid+insulation