Welded Wire Fabric - Concrete Reinforcement Mesh Guide

Welded wire fabric is a prefabricated steel reinforcement mesh made from intersecting wires welded together to help control cracking in concrete slabs and flatwork.

Welded Wire Fabric diagram — labeled parts, dimensions, and installation context

What It Is

Welded wire fabric, often called WWF or wire mesh, is placed in concrete to provide distributed reinforcement across the slab area. It does not replace proper subgrade, control joints, or structural reinforcing where required, but it helps limit crack width and keep the concrete acting more uniformly.

Its performance depends heavily on installation. If the mesh stays on the ground instead of being supported in the slab, it provides much less benefit than intended.

Types

Common types vary by wire gauge, spacing, sheet size, and whether the product comes in flat sheets or rolls. Heavier welded reinforcement is used for more demanding slab and pavement applications.

Where It Is Used

Welded wire fabric is used in sidewalks, patios, driveways, garage slabs, basement slabs, and other concrete flatwork. It is common where distributed crack control reinforcement is needed over a broad area.

How to Identify One

It is usually visible before a concrete pour as a grid of welded steel wires laid over the slab area. After the pour, homeowners usually only know it is present from plans, invoices, or photos taken during installation.

Replacement

Welded wire fabric is not usually replaced in an existing slab by itself because it is embedded in the concrete. It becomes relevant during new pours, slab replacement, or major concrete repairs where reinforcement details are being corrected.

Welded Wire Fabric — FAQ

What is welded wire fabric used for in concrete?

It helps control cracking across slabs and flatwork by distributing reinforcement through the concrete. It is common in sidewalks, patios, garage slabs, and other broad concrete surfaces.

Is welded wire fabric the same as rebar?

No. Rebar uses larger individual bars placed at specific locations, while welded wire fabric is a grid of smaller welded wires spread across the slab area. They can serve different roles and are sometimes used together.

Does welded wire fabric keep concrete from cracking?

No concrete reinforcement prevents all cracking. Its job is to help control crack width and keep the slab more stable after cracking occurs.

Why does welded wire fabric need chairs or support?

If the mesh lies on the subgrade during the pour, it ends up too low in the slab to do its intended work. Chairs or other supports help keep it embedded at the correct depth.

Can I add welded wire fabric to an existing slab?

Not without replacing or overlaying the concrete, because the fabric has to be embedded in the slab. It is a planning and installation choice made before or during the pour.