How Far Apart Do You Cut Expansions in a Concrete Driveway?

Spacing

• Expansions, also known as control joints, are cut in straight lines to form a grid. The distance between each expansion is measured in feet and should be two to three times the thickness of the driveway slab, which is measured in inches. For example, the expansions in a 4-inch-thick driveway should be between 8 and 12 feet apart.

Depth

• Like the spacing, the depth of the expansions is determined by the thickness of the slab. It should be equal to 1/4 the depth of the driveway. For example, a slab that is 5 inches thick calls for expansions 1 1/4 inches deep. Cutting the expansions too shallow won't provide enough space for the slab to expand and contract as it needs to and can result in unsightly cracks.

Cutting Expansions

• The process of cutting expansions in concrete is not complicated, but it requires precision. Once the spacing is measured, snap chalk lines across the surface to guide the saw while you're cutting. Spray the lines with lacquer to prevent them from fading before the cuts are made. Position the blade setting of a concrete saw to the correct depth, and cut each chalk line from one end of the line to the other.

Safety

• Cutting into concrete creates dust that is harmful to your health. Protect your eyes with goggles, wear a face mask to avoid breathing in the dust and put in ear plugs so you don't damage your hearing. Also, use a wet saw to limit the amount of dust produced and make sure that the hose is securely attached before cutting.