Remove Drylock before rigid foam?
I’m finishing part of my basement and will be using rigid foam to insulate the block foundation wall. The basement never feels humid and never had a musty smell, but twice in 10 years we’ve had some water weep through the walls. The previous owner dealt with water issues by using something like Drylok (it’s a yellowish/off white color) on the walls, which was done at least 20 years ago. I repaired the storm drains (old Orangeburg pipe is gone and storm water makes it to the street again) and have an interior french drain going in soon. They’ll also drill weep holes into the bottom block to keep the voids in the block from filling with water. That should limit the water against the foundation and give it a place to go if it comes in.
My plan is to put a dimple membrane on the wall to allow any water that weeps through to run down into the drain and then rigid foam over that. The existing Drylok is a good shape other than a few areas where it’s flaked off. Is there any issue covering the wall as is, or should I try to strip the old coating off? When I’m done the wall will be covered with XPS, and I’m not sure if the existing Drylok will cause any issues once the wall is sealed with rigid foam. Bare block and XPS aren’t surfaces mold can grow on, but I’m not sure about whatever this old coating is. Once the foam is up the wall won’t be able to dry to inside as easily as it can now. I’m in climate zone 5a
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