Placing Rebar Under a Concrete Patio

man working on rebar for a foundation
  • 16-32 hours
  • Intermediate
  • 200
What You'll Need
3/8-Inch rebar
Stones or rebar supports
Wire Reel
#9 Klein Lineman's pliers
A Pigtail &
Twist Ties

Installing a concrete patio requires more time, more work and more costs than some other patio materials, but in the end, it will eventually pay off once it is done. Concrete patios are very durable, and with a little landscaping, can be transformed into something that will complement your garden or your entranceway. An important step to keeping your concrete patio looking its best is to add rebar. These reinforcing bars actually keep the concrete intact and also help prevent (not stop) the formation of cracks.

Rebar Basics

There are different sizes of rebar available for all kinds of construction projects. For concrete patios, use #3 rebar. These bars have a 3/8-inch diameter. The soil under the patio will provide most of the necessary support for the concrete. The rebar installed is intended to minimize cracks caused by the concrete shrinking and swelling depending on the temperature and weather conditions. It will also, however, help keep the slab from breaking if the soil under the slab sinks or shifts over time.

Step 1 - Lay the Rebar Evenly

rebar twisted together for structure

Installing rebar is critical to the long-term strength of your patio. Therefore, it should be properly and evenly positioned. Lay the rebar every 24 inches in both directions inside the form for the patio slab. The rebar should form a neat grid. The ends of the bars should be two or three inches from the sides of the form to protect the rebar from the elements.

Step 2 - Twist the Wire Pieces

Using the rebar tying tool, twist wires around the intersections of the bars. This will hold the rebar into its position and maintain its grid-like pattern while the concrete is being poured.

Step 3 - Lay the Supports

For rebar to be most effective in something like a concrete patio, it should be placed in the center of the slab, or as close as possible. The stones or rebar supports are intended to raise the rebar off the ground towards the center of the slab. Choose stones or supports that have the proper height to reach the middle of the slab. Provide enough supports that when the rebar sits on top it does not sag between support points.

Step 4 - Pour the Concrete

a concrete patio

You may now pour the concrete mix into the form. This concrete will flow beneath and above the suspended grid of rebar. After the concrete has been evenly spread out, cover your project with plastic and let it cure for seven days. The plastic will retain the moisture that is important to the chemical reaction that causes concrete to harden, as well as protect your patio from the elements. Remove the plastic cover after one week and allow the concrete to set for an additional 14 days before using the patio.