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EPDM sheet along BSMT wall grade, under mulch: Cheap fix or disaster?

5723 Views 4 Replies 5 Participants Last post by  Aframe
See Illustration 1 (elevation)
Gable-end wall (no overhang or gutter) with a damp interior basement wall. I graded the "soil" (200% clay) away from the wall at approx 1-inch-per-foot out to 8 feet, where there's a swale graded to carry water away parallel to the wall.

See Illustration 2 (plan view)
There's a stacked block retaining wall at the house corner. I can't dig lower than its base, which kept me from increasing the grade of the slope beyond 1" in 1'. Also the secondary grade of the swale (parallel to the house wall) had to be maintained - another limitation.

I'm trying to ensure drainage away from the basement by installing a 48" wide EPDM sheet along the wall and covering with mulch per Illustration 1. Water to drain away from the wall for 8 feet, and then drain parallel to the wall along a sloped swale.

QUESTION 1: Will the EPDM sheet actually have the opposite effect? Might it keep the soil (clay) beneath it constantly wet/damp by not allowing it to dry normally?

QUESTION 2: Per Illustration 2, there seems to be a half-baked DIY footer poured against the cinderblock wall--decades ago--to support brick veneer. Will the EPDM sheet destabilize the soil beneath it (maybe by but not allowing the soil to dry normally) and thereby jeapordize that footer?

Yeah, this is an oddball first post :whistling My contracted work is generally interior only, but I'm attempting to provide a simple, inexpensive fix (beyond my normal scope) for a good client who's prepping her house for sale. She's financially strapped and I'm "not so busy" at present, we are. Any knowledgeable advice / POV is much appreciated. Tom


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I have done this before to solve damp basement problems. It will not help a wet basement. I see it as similar to the moisture barrier in a crawl space. The soil under an interior footing seems to be just fine. The tough part is to get the owner to not punch holes in the epdm for plants.
from your drawing, the water might be coming in from the brick cavity. brick is not water proof. it leaks and requires weeps to get the water out. for the install you show there should be a flashing that interrupts the water before the brick goes below grade to the brick ledge. there should be weeps visible above grade too.
Do you have the space to pipe the water away before or as it enters the swale? Get it away before it can soak in.
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