DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   General DIY Discussions (
-   -   Cape Cod "Crawl Space" Flooring DAMP (

Jimbotta 08-02-2009 09:18 PM

Cape Cod "Crawl Space" Flooring DAMP
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 08-03-2009 06:00 AM

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 08-03-2009 06:06 AM

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 08-03-2009 08:12 AM

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

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


All times are GMT -5. The time now is 09:43 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1