Is the surface of your concrete driveway, patio or basement floor flaking away? Do the patches get bigger and more numerous each spring? The problem is called concrete spalling, and here's how to fix it—without replacing the entire driveway.
If your driveway surface is spalling, the most likely cause is an installation mistake. Common mistakes include adding too much water to the mix, to make it easier to pour; sprinkling the surface of the concrete with water, to extend finishing time; and not curing the concrete properly after installation.
Resurfacing your driveway, patio or basement floor with a 1/2-in. concrete overlay fixes the problem. Enlist a couple of helpers and overlay the concrete surface one section at a time. A section is an area about 10 x 12 ft. that is defined by the existing control joints. Before starting, power wash the entire surface and brush it with a stiff broom and a cleaner/degreaser concentrate available from the hardware store.
The technique we show below can be modified for resurfacing concrete patios and basement floors.
Use this diagram to help you lay out the furring strips and concrete “picture framing” strips you'll need when resurfacing your driveway.
This detail shows how the furring strips that run along the outside edges of the driveway are anchored using stakes.
This detail shows how the plywood picture frame strips are anchored with concrete nails. These strips define the interior edges of the concrete section to be resurfaced.
Here's the short course on how to install a concrete overlay:
Stake 1x2 furring strips along the edges of the driveway or patio, keeping them 1/2 in. above the existing surface. “Picture frame” the section by nailing 1/2-in. plywood strips, flat to the concrete, along the control joints.
Mix one part Type 1 Portland cement and one part fine sand by volume. Add water until the mixture is the consistency of thick paint, then brush it on the damp concrete.
Before that dries, mix three parts fine sand and one part Portland cement in your wheelbarrow with enough water to make the mix the consistency of thick oatmeal. Shovel the mix into the formed area and level it with a straight 2x4 spanning from one side of the forms to the other.
Smooth the surface with a bull float, round the edges along the forms with an edger, and finish the surface with a finishing broom. Timing is the secret to getting a nice finish. Use the bull float immediately, but wait until the concrete stiffens before using the edger and broom. All the tools you need are available at most rental stores. Cover the finished concrete with plastic for five days or spray it with a curing compound.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.