The use of rebar and wire mesh in a concrete slab depends on various factors such as the size of the slab, the load it will bear, the soil conditions, and the local building codes. Here are some general guidelines:

1. Rebar (reinforcing bar): Rebar is commonly used in larger concrete slabs or in areas where heavy loads will be placed on the slab. The rebar helps to reinforce the concrete and prevent cracking. The size and spacing of the rebar will depend on the design requirements and load conditions.
2. Wire mesh: Wire mesh is often used in smaller concrete slabs or in situations where it may be difficult to place rebar. Wire mesh helps to distribute the load across the slab and can also help to prevent cracking.

Oblong Square Crimped Mesh

In many cases, a combination of rebar and wire mesh may be used for added strength and durability. It's important to consult with a structural engineer or a professional contractor to determine the specific requirements for your concrete slab based on the factors mentioned above.

In summary, while rebar and wire mesh are not always required for every concrete slab, they can provide added strength and durability, especially for larger slabs or those subjected to heavy loads.