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After tearing out subfloor, there's mold and moisture on slab

956 views 1 reply 2 participants last post by  oh'mike 
#1 · (Edited)
Ever since we bought this fixer, it has had a musty smell that seems to come from a converted 'bedroom' that had formerly been a garage. When I tore out the wallboard to install insulation, I saw horsetail plants (moisture indicators) growing up the sides of the shiplap walls and into the attic. Now I have removed the 2X4 and plywood floor that had apparently been installed over top of the garage floor, back in 1966 according to an old newspaper they considerately left behind under the floor.
Anyway, under the sheet of plastic below the 50-year old floor construction is trapped moisture and loads of black mold. It seems that they did not fill any of the cracks or seal the slab before they laid the plastic and built the floor on top.

I want to clean the slab, fill the cracks, seal the slab, then rebuild the floor. BTW, the house has no eaves, sits at the bottom of a hill in rainy Seattle, and is just inches above the water table.
What I need is advice on the following:
1. What method of mold removal will not interfere with a good slab sealer? I've noticed that many sealers tell you not to pre-wash the cement with soap, as it may inhibit the sealer from adhering properly. Would hydrogen peroxide be good?
2. I need to fill deep cracks in the floor slab and also cracks in the sides of the concrete wall foundations. Any advice on which type of crack filler product would be best? Something thick or something watery?
3. I need a good slab and foundation sealer. I've read reviews of dozens of products and still need some advice on which would likely be best for my project.
4. Lastly, is there any brand of rigid foam insulation that would be good for putting under the rebuilt flooring?
Any advice would be greatly appreciated. Thanks!
 
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#2 ·
Welcome---

If you have pressure under the slab--no sealer that I know of will be a permanent fix.

The water will push the sealer off in short order.

We have several knowledgeable concrete contractors here--one will be along soon.
Please be patient.
 
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