I have a 50 year old backsplit, with a minor mould problem in the crawlspace. There are a couple of wet spots that can be fixed with simple exterior grade changes, and one spot that will need to be trenched and sealed. The other issue is the floor in the crawlspace. It's just about the crappiest concrete I've ever seen. It was not trowelled at all, and looks like they used a garden rake to spread it. It's also a bit hollow sounding. This has lead to some rising damp in the crawlspace, which causes mould to grow on the manky floor.

After I have a soda-wash done on the walls and floor, What are my options to repair this?

Obviously, I could chip it out and have a new floor poured, but this is a lot of work for minimal functionality. What are some other options to seal/repair this from the inside?


After you have done the wash, paint the floor with Drylok. In your case it would be best to use a economy grade paint sprayer given the roughness of the concrete. It will seal out the moisture (mold's happy place), and it will also keep out the bugs and plant roots in most cases. Yes, the ultimate solution would be to chip out the old floor and install a new one correctly, but if you are looking for a fix that will work nicely and not need a new back for you, go with the Drylok.

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