Found a surprise in the wall on Day 1 of basement reno
We live in Atlantic Canada in a split-entry home with 4 foot high concrete foundation walls in the finished basement (creates a ledge all around the basement). We’ve had to keep a dehumidifier going in the summer to control humidity and mold growth on baseboards, so I anticipated the wall construction to be traditional batt and poly over the concrete. I planned to counter some of that migrating moisture by adding either closed cell spray foam or XPS behind the existing studs, depending on what I found for available space. I broke open a small hole between studs in the finished wall in our basement today and was elated to also find 1″ EPS behind the studs! However, I know that proper installation is to SEAL all of the insulation seams and edges to prevent moisture migration, so my question is… Do I really need to remove all of my drywall just to seal the seams and edges? Should the poly be removed or is it beneficial enough to prevent the need to tape up the seams?
Also, I lifted an edge of the carpet to find the 1/2″ underlay glued directly to concrete (expected), but the only evidence of moisture was the slight rusting of the nails in the carpet nailing strips, no sign of mold. The wood strips were not even discolored. I had also planned to install insulation and plywood over the concrete slab because I’m not confident there is a vapor barrier under the slab, but I must be feeling lazy because I’m now questioning the need for it. Would the lack of vapor barrier under the slab be the cause of high basement mold in summer, or could that simply be from the open screen door which is only a half-flight of stairs away? (The basement is open to the stairs and is not well sealed to the adjacent garage). Any advice?
Thanks in advance,
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