Insulating an Existing Slab
Looking to insulate the slab of an 1950s home as part of large scale energy retrofit. Zone 5, decently drained lot but with clay soil that retains moisture. The rest of the home will be well sealed and insulated with new windows.
The floors aren’t coming up, so foam or barrier under isn’t an option. There appears to be some thin plastic barrier in place under the sub floor.
All that said:
1.) After digging away from the foundation I’ll apply a membrane to the foundation wall to keep moisture out.
Recommendations on a product? I’ll only be able to get the wall so clean, I worry about proper adhesion.
2.) Should I aim for 2′ or 4′ down? 4′ is a lot more work, is the extra gain worth it?
3.) Planning to put 2.5″ EPS on. What’s the best method? Furring strips sunk into the slab? Direct anchor into the concrete/block? Adhesive? I’ve read of people using all methods.
I’ll seal the seam between the footer and the slab well, before any of this. Will cover any exposed EPS with metal.
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