Installing Plastic Around Foundation
doormatt
| Posted in Construction Techniques on
Thinking of installing 6mil plastic sheating around the perimeter of my walkout basement slab to help with waterproofing. The plastic would start about 8″ up the wall sheathing, run down the exterior face of the slab, turn over the top of the foundation, and then run about a foot or two away from the house. I’ll then backfill with gravel to allow drainage. I’ve read several websites that suggest doing this and others that say not to – that it will actually trap moisture in the foundation. Which is correct?
Replies
Don't!
That will trap ground moisture and direct it to keeping thrt bottom 8" of sheathing wet. You will have mold there in a couple of years destroying the wall.
What you need is tarpaper or a housewrap on the wall itself and tcked up uder that upper level
So the plastic is out... how far down the wall would you extend the tarpaper? I've provided a couple details showing my exact conditions. In condition 1 I'm worried about water collecting on the footing and then running back under the slab. In condition 2 I'm worried about water running down the wall and then back under the slab at the exposed joint between the slab pour and wall pour.
I'm sloping all grade away from the house towards a french drain system. I'll be installing a pvc skirtboard with fiber cement siding above. I plan for the bottom of the skirtboard to be about mid-depth of slab (bottom of grace vycor). The soil around the house is pretty much sandy clay - so it will suck up moisture. Do you see anything else I should be concerned with or need to address?
Th equestion is not how far down, but how far up this wall to run the tarpaper
Start it an inch below the top of crete slab and run it up and under the siding above.