We are planning to finish this basement room (frame, drywall) and we noticed, after emptying it out and after this unreal amount of spring rain we've had, that there were moisture spots on the walls here and there. Never saw before (white painted wall). Knowing ill effects on drywall we had a group come out and assess a solution and they did something similar to a French Drain install:
They jackhammered away most of the floor about from the two earth-facing walls, 1' out into the room and dug down laying, I believe, gravel and into that a periperated, corrugated plastic pipe leading to a sump pit with pump installed at the end of the room. They then pierced every cinder block section at the base allowing water to drain out and places a ridged plastic sheet against the bottom of the wall, then re-layed concrete, part of the plastic sheet raised above the floorline. This should solve moisture issues completely I am told - no more block filling with water, leaking.
But will there not be moisture from the earth venting up thru the plastic ridged sheet, through the very route that the water would drain from block down into the pipe? Would this minor moisture not cause issues with drywall, even though the block will no longer be moist? Or should this just take care of it?
There was never dripping water, just moist patches - no water pooling, etc.
Thanks.
bp