Concrete Crack Repair & Joint Sealing

Not every crack is a problem, and the first job in crack repair is deciding which kind you have. A slab that has never cracked does not exist; concrete shrinks as it cures and rides ground that moves, so hairlines are the normal cost of doing business. Spending money to chase harmless cracks is as common a mistake as ignoring the ones that actually matter.

Read the crack before you seal

The line that matters is movement. A tight hairline is a finish issue. A crack that opens in a dry August and tightens after a wet winter is a working crack, riding the clay. A crack with one side sitting higher than the other is displacement, which means the ground under part of the slab shifted, and no amount of sealant addresses that.

Routing and sealing done right

Sealing a crack is not squeezing a tube into a gap. Done properly, the crack is routed, cut open into a clean channel wide enough to hold sealant, then filled with a material matched to how much the crack moves. A working crack wants a flexible sealant that stretches with it; a static repair can take a harder material. Get that backwards, and a rigid filler in a moving crack simply cracks again right beside the repair.

Joints need maintenance too

The control joints a crew cut into your slab are not a one time detail. Over the years the sealant in them shrinks, hardens, or pulls loose, and an open joint lets water into the base exactly the way an open crack does. Resealing joints on a schedule is cheap upkeep that protects an expensive slab, and it is the small maintenance that quietly adds years to a driveway or patio you already paid for.

The goal is keeping water out

Here is the part most homeowners miss: sealing is not mainly cosmetic. The real purpose is keeping surface water from running down through the crack into the base. On Georgetown clay, water reaching the subgrade is what drives the swelling and shrinking that moves the slab in the first place, so an open crack feeds its own growth. Seal it and you slow that cycle; leave it open and every downpour makes it worse.

Published industry cost data puts crack and joint work between $400 and $2,000, depending on how much routing, sealing, and joint maintenance the slab needs. It is cheap next to a repour, and on a sound slab it is money well spent. If the cracking is widespread rather than a line or two, though, you may be facing a driveway repair question instead, and our guide to why concrete cracks here sorts the harmless from the expensive.