[Jimbotta]

Looking for some help regarding my Falmouth Cottage, and moisture and dampness coming up via the crawl space or sub basement into my floor rug. I would like to take up the rug and install some Porcelain tile over the plywood subfloor. However, I assume that the tile and grout will crack over the years from the moisture coming up through the plywood flooring. (There is only the plywood sub flooring.) I was thinking of stapling 50ml. Poly to the joists under the house, or should I install insulation--the hard foam board or R-25 type placed in-between the floor joists with wire supports that you mentioned recently? If so, will the insulation stay dry?
I can lay Ploy on the sub basement sand/ground for when it rains--the water will eventually come in from outside and "puddle" on the poly. This is indeed a big Conundrum.
Thanks Jimbotta:thumbsup:

 

[Just Bill]

First, you need to address the water problem. Working gutters/downspouts that get water away from the foundations and grading that does the same thing, will eliminate 90% of your water problems.

Then, lay 6mil plastic on the crawl space ground and up the sides of the foundation. The underside of the floor/joists, should be insulated with the moisture barrier going towards the heated side(on the underside of the floor). That should dry things out.

Tile requires a min of 1 1/4 of very rigid subfloor, so you will probably have to add to the existing subfloor.

 

[Jimbotta]

Cape Cod Sand Crawl Space --Wet when Rains

Thanks Bill,

What type of Moisture Barrier-- A Ty-Vek house wrap or Foam Board??

- Regards, Jimbotta

 

[ChemE]

Here's an article from Building Science that will help you out:

http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces

I would use spray foam on the underside of the floor and joists as discussed in the article.

Enjoy.