4079 Townsend Ln

Water is the whole problem

An open joint is a funnel. Rain runs off the slab, finds the gap, and goes straight under the concrete instead of off the edge of it. Once water is under there it does three things, and none of them are cheap to undo.

• Winter splits the concrete. Water sitting in a joint freezes and expands. Every freeze wedges the crack a little wider, and the edges start to break away. That is why the worst damage on a driveway almost always starts at a joint.
• It washes out the base. Water running under the slab carries the soil and gravel with it. The slab loses its support, then it settles, then the panels no longer line up.
• It finds the house. The joints at the garage and the front entry sit right against the foundation. Water in those runs along the wall and looks for a way in, which is how a dry garage turns into a damp one.

What we used

We cleaned the joints out, then sealed them with Sika. It is a flexible polyurethane sealant, not a rigid filler. Concrete moves with the temperature, and a rigid patch cracks out of the joint the first cold snap. This one stretches and compresses with the slab, which is what makes it a lasting fix rather than something you redo next year.

Then we broadcast sand aggregate into the surface while it was still wet. That is the reason the joints look like concrete and not like a bead of caulk. The sand picks up the color and the texture of the aged slab, so the repair disappears instead of leaving shiny gray lines down your driveway.