Rebar vs. Wire Mesh: Which Reinforcement is Right for Your Slab?

Concrete is incredibly strong under compression (pushing) but weak under tension (pulling). Reinforcement provides the tensile strength needed to hold a slab together when the ground shifts, the concrete shrinks, or heavy loads are applied. Understanding the difference is key to a long-lasting project.

Wire Mesh (WWF - Welded Wire Fabric)

Wire mesh consists of thin steel wires welded into a grid. It is sold in rolls or flat sheets.

Pros: Excellent for preventing "plastic shrinkage cracks" (small surface cracks that happen as concrete dries). It is relatively inexpensive and easy to transport.

Cons: It provides very little structural support. Its biggest flaw is installation—contractors often lay it on the ground and try to "pull it up" as they pour. This almost never works, leaving the mesh at the bottom of the slab where it does zero good. To be effective, it must be supported by "chairs" to keep it in the center of the slab.

Rebar (Reinforcing Bar)

Rebar is the heavy-duty option. For most residential slabs, #3 (3/8") or #4 (1/2") rebar is used.

Pros: Massive structural integrity. It can actually bridge small voids in the subgrade and hold the concrete together even if it cracks due to extreme ground movement. For driveways, rebar is the gold standard.

Cons: It is significantly more expensive and labor-intensive to install. It must be cut with a saw and tied together with wire at every intersection.

The "Concrete Cover" Rule

Whether you use mesh or rebar, the metal must be protected from the elements. If steel gets wet, it rusts; as it rusts, it expands and cracks the concrete from the inside out (spalling). A standard 4-inch slab should have the reinforcement exactly in the middle—2 inches from the bottom and 2 inches from the top.

Before you buy your steel, use our slab calculator to ensure your dimensions are correct so your reinforcement grid is laid out perfectly.