Concrete steel mesh is a reinforcing material placed within a concrete slab to prevent cracks that form in the slab from spreading throughout the material and causing possible breakage. Standard wire mesh is useful for smaller slabs such as concrete counter tops or patios, and a larger, welded, rebar grid mesh is used for thicker slabs of concrete intended for roadways or foundations. The basic installation process is the same regardless of the size with a support structure placed beneath the mesh to hold it in place followed by the concrete pour.
Line the base of your foundation or concrete form with a support structure for the steel mesh. Use concrete blocks about 3-inches square, cut to half of the slab's height, and spread the blocks throughout the base of the foundation about 3 feet apart as your support base. Make sure all of the blocks are the same height to ensure that the mesh is held in the center of the slab without moving as the concrete is poured.
Substitute plastic support chairs for concrete blocks if you cannot find a supply blocks of a uniform size. The support chairs are small plastic structures that sit flat on the base of the foundation and have a small dip at the top to hold the mesh in place.
Measure the foundation length and width with a tape measure. Subtract two inches from both the length and width so that the mesh isn't exposed at the edge of the concrete. Cut the mesh to fit the adjusted measurements taken and place within the foundation hole on top of the support blocks or plastic chairs. If you require multiple mesh pieces, then place them overlapping one foot along the edges and lashed together at the overlap using steel ties. You'll want the entire foundation covered with the mesh so that the steel extends throughout the slab, within 2 iinches of the slab's edge.
Pour the concrete into the foundation hole from a corner of the foundation. Spread the concrete with a concrete rake or spade, covering the mesh with the material. The supports, either the stone blocks or the plastic chairs, will keep the mesh in place at the height of the tops of the stones or chairs in the center of the slab, preventing it from sinking to the base of the foundation.
Finish and cure the concrete normally with the reinforcing steel mesh resting in the center of the material.