Replace basement slab? Cost?

4 years ago

Hi all,

Background: we're gutting and renovating our home in Toronto, including the basement. Basement square footage is around 1300sf.

Currently the basement slab abuts the foundation, they do not overlap. We can see that the concrete around that joint is darker and feels a bit wetter than the rest of the slab.

In addition, the slab is really wavy and uneven - we were going to pour gypcrete to level it, but the gypcrete person said that she wasn't sure it would adhere properly to the parts of the slab that have moisture.

It's very clear from simple observation that the moisture is coming up through the crack between slab and footing, not through the walls.

We're at the top of the hill and even with all the flooding in recent years, our basement has never flooded.

Decision: So now our builder is suggesting that we replace the slab, this time pouring it so that it overlaps the footing. They would also be installing interior weeping tile, and the slab would be poured over gravel and insulation and vapor barrier. According to his quote, this will cost $24,000. It sounds like a ton of money to me. Is it in the ballpark of what a new slab should cost? Should we:

a) bite the bullet and replace the whole slab with our builder; or

b) go get some other quotes to do the slab (is that a faux pas when already working with a gc?); or

c) forget about slab replacement, put down some DryBarrier or DryCore and live with the fact that the floor is uneven?


(thanks in advance)

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