Finishing concrete block wall basement

Hi- I am a new homeowner that purchased a raised ranch home with a floating slab basement. I've noticed the foundation block walls get wet after rainfall and I have added down spout extensions and also regraded around the perimeter of the foundation. The block walls seem to be ok now, but in the cove joint I do feel a little dampness still in some spots. There hasn't been any pooling water or anything- just some light wetness. I am planning on putting up continuous 2" xps foamboard along the foundation block walls and framing in front of it for drywall (probably the moisture-resistant kind). There is a sump pump and I plan on running a dehumidifier 24/7. So far, I haven't had a humidity above 56% (including when dehumidifer wasn't running). I have a few questions- The cove joint is about 1" wide, so the 2" foamboard would essentially block the joint from breathing. Should I leave a small gap so that the cove joint can breathe a little? Or is it better to block the cove joint off? Hypothetically if a downspout got clogged and water was dumping near the foundation, I'd expect the block walls to be saturated with water like they had been historically. If the blocks get wet behind the drywall, how would they dry if there is drywall in front of them? Would a small gap between the floor and wall structure be enough for air circulation and to allow the moisture to escape and not create a very humid micro climate behind the wall? I'm basically just trying to figure out the best way to go about finishing this basement, as it is half of our total living area. I'm open to literally any suggestions or pointers that I may be missing, and will answer any questions I can. Thanks!! submitted by /u/Exotic-Credit-2241 [link] [comments]

May 13, 2025 - 20:50

Hi-
I am a new homeowner that purchased a raised ranch home with a floating slab basement. I've noticed the foundation block walls get wet after rainfall and I have added down spout extensions and also regraded around the perimeter of the foundation. The block walls seem to be ok now, but in the cove joint I do feel a little dampness still in some spots. There hasn't been any pooling water or anything- just some light wetness.

I am planning on putting up continuous 2" xps foamboard along the foundation block walls and framing in front of it for drywall (probably the moisture-resistant kind). There is a sump pump and I plan on running a dehumidifier 24/7. So far, I haven't had a humidity above 56% (including when dehumidifer wasn't running). I have a few questions-

The cove joint is about 1" wide, so the 2" foamboard would essentially block the joint from breathing. Should I leave a small gap so that the cove joint can breathe a little? Or is it better to block the cove joint off?
Hypothetically if a downspout got clogged and water was dumping near the foundation, I'd expect the block walls to be saturated with water like they had been historically. If the blocks get wet behind the drywall, how would they dry if there is drywall in front of them? Would a small gap between the floor and wall structure be enough for air circulation and to allow the moisture to escape and not create a very humid micro climate behind the wall?

I'm basically just trying to figure out the best way to go about finishing this basement, as it is half of our total living area. I'm open to literally any suggestions or pointers that I may be missing, and will answer any questions I can. Thanks!!

submitted by /u/Exotic-Credit-2241
[link] [comments]