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Concrete slab drift sealing

by Don Penner
(Toronto, Ontario)

Q. I have a poured concrete slab that butts up against my home and foundation. It has drifted about 3/4" away from the house (perhaps caused by shrinkage or frost heaves). The gap is too wide and deep for typical sealer. What can I do to fill these gaps? Should I use patching or are there other products that will seal this to continue to help water flow away?

A. The best thing to do is fill it with a rough grade polymer material. It's like filling it with concrete, but the polymer material doesn't shrink near as much as concrete. The polymer overlays come in smooth and rough grades. The rough grade has bigger aggregates and can be applied with some thickness. These materials usually dry very white, so you may need to stain or paint it so it's not such an eyesore.