Hello,
I’m starting the process of insulating my basement and will eventually finish it as living space.
The former owner (many years ago) covered the walls with 1″ poly-iso with foil facing exposed and the cardboard facing glued directly to the concrete walls.
The house is 90 years old and the walls are in great shape allthough the old concrete is quite coarse. There’s a few small cracks and a small section missing where the water and sewer lines come in through the foundation. There’s never been a drop of water down there in the almost 3 years I’ve been here (even in two very wet springs) but when I removed the poly-iso from the wall I found a fair amount of efflorescence. Not continuous, but patchs of it.
The grading of the lot is ideal. I’m on a hill where the street carries away all the ground and surface water coming down the hill and the steep slope of the land carries it away in the back. The soil is all blue shale in my area and when I took out my old slab I found nothing but gravel and bedrock. Based on this I don’t think water is the problem, or not any quantity of it at least.
Should I clean the efflorescence off with etcher… Is it worth the time and money to put drylok or someother concrete sealing paint on the walls before I cover them up?
I was thinking that maybe the cardboard in direct contact with any wicking moisture was possibly the cause. That and/or cool damp basement air in the summer. As my slab was curing my concrete walls felt dry but droplets of water formed on the few spots where the cardboard facing was left behind by the glue
I was planning to patch any visible cracks with hydraulic cement, cover the walls with 1″ XPS, tape the joints, frame a 2×4 wall, insulate with unfaced fiberglass batts, then use the airtight drywall approach to air-sealing.
Ideas????
IJ
Replies
You could probably search archives on this subject, and I have an older FHB issue that discusses this. It caused a lot on controversy, but the predominant concept was to put a vapor barrier from the basement floor to at least above the ground level, like six mil plastic. You can't prevent hydraulic pressure from outside with interior sealants, so you need to figure why moisture might be getting in, be it gaps in the wall or bad grading outside (or that big shrub against the wall). I went with the plastic, furring for the foam insulation, and drywall afterward. Worked so far.