Part of my basement as for insulation foam boards glued to the concrete
walls dow to about 6 inches from the floor. I've noticed recently some
seepage at the base of one of the foam boards. Thinking it could be a
leak, I removed the foam board to investigate. The entire wall was wet
underneat. It seems like condensation is forming behind the foam
boards. The concrete is chipping on the surface as a result of this
I'm currently letting it dry but I'd like to know how to prevent this
when I'll re-insulate that part of the basement.
Id say the 6" was left because the wall leaked from the outside, its an
airspace as I have instaled a 2"bottom airspace. Let it dry , use a
moisture meter to see if it realy dries. But its likely best to leave it
removable and consider outside repairs, Condensation forms on the
coldest wall, insulation may be reducing it but trapping it. Keep an eye
out for mold and use bleach if its detected. I also use foamboad on my
I would suggest a closed cell spray on foam insulation like Tiger Foam
instead of foam boards. The liquid 2 part foam adheres to the blocks or
concrete completely and will seal the wall as long as it's dry when you
apply. The air pocket behind the foam board is likely the cause of the
condensation. When you seal it completely, you elimate the gaps and
there won't be any condensation. Also, the foam board is only a third
of the R-value of the spray foam kits, which will further reduce or
eliminate the thermal bridging that is causing the condensation.
If it's a leak, as in crumbled or cracked blocks from the outside, you
would want to fix that, and you would know that by the amount of water
and if it's just coming in during extended rain periods or high water
table times. Most likely it's a condensation problem from how you say
Good luck and happy holidays!
Actualy abi foamboard foilfaced is R 7.2"
Icynene spray on is R 5". Polyurethane spray on is R 7.2" but it
outgasses. Same products, one sold finished, one in liquid bulk.
Your removable boards are best as future repairs and monitoring of
leaks can be done, spray on foam can hide a major issue.
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