Here’s a handy, albeit highly incomplete, video on insulating your crawlspace:
- They installed it with the vapor barrier put firmly up against the floor of the room above – this is actually correct. Most people install it upside-down and staple the paper vapor to the floor joists – this is totally incorrect. When you do that, you end up with moldy insulation like shown here.
- They stressed the importance of air sealing and even showed the band joists (technically called the “rim joist”). Kudos for that!
- They noted the importance of installing a vapor barrier on the floor, though they should have mentioned that you typically only do that for a dirt floor. They should also have mentioned that just laying plastic on the floor won’t do much to stop moisture from coming up. Any place air can flow, water vapor will go!
- They used fiberglass (of course) on the rim joists. Unfortunately, this can lead to moisture damage. See this excellent article in Fine Homebuilding (PDF file) on insulating the rim joist.
Superb video on a crawlspace sealing system
The next (commercial) video presents the situation in crawlspaces accurately and proposes a solution that appears to be done thoroughly and professionally. Note that I have no personal experience with the company that produced the video. Regardless, it is well worth a view.
Here’s a very nice article on insulating your crawl space by the Dept. of Energy. They get the rim joist insulation wrong though…
Fine Homebuilding article showing the proper way to insulate the rim joist.
Family Handyman article on installing a vapor barrier in your crawlspace.