Sealing Crawl Space floor
BobHr
| Posted in General Questions on
What is the recommended material for sealing a crawl space floor. How is it attached to the block wall.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Robert,
There are a number of vapor barriers designed for such applications. Some are just thick poly (10 mils), and others are cross-laminated or otherwise reinforced to increase tear resistance. I use Tu-Tuf, which comes in a smooth white version (#4) or a slightly ribbed translucent version (XF), which is a little more pliable and better for traction. They are only 4 mils thick but much more tear and puncture resistant than conventional poly, and have no pinholes.
They're available from Energy Federation (http://www.efi.org/) and other suppliers.
I forgot the second half of your question.
The best way to seal the VB to the block walls is with Tremco acoustical sealant, which is a non-hardening butyl rubber caulk, or any other polyethylene-compatible adhesive caulk such as urethane (PL Premium). With the Tremco, you'll have to attach wooden strapping over the edge of the VB and nail with a powder-actuated nailer to hold it in place. With the construction adhesive, it should be secure without strapping. Obviously, the block will have to be clean and dust-free.