What is the difference between rebar and wire mesh in my concrete?

If you have been calling around getting prices for a new concrete driveway, the topic of reinforcing has probably come up. From what I hear, a lot of Contractors in this area are still using wire mesh, A.K.A. welded wire fabric (wwf). It has been quite a few years now since we have used wwf. Whenever blueprints call for wwf we have it substituted with a #3 rebar grid 20″ on center. It is something we do not believe in and could never offer a warranty on. Before taking this stand we had 3 jobs in a row, containing wwf, randomly crack. Coincidence? Perhaps, but I have made some observations I will share.

WWF comes in a large sheet or roll depending on the gauge of wire used. The wwf is laid flat on the prepared sub-grade and as the concrete is placed, the mesh is pulled up with a hook or claw hammer. It all seems pretty legit at this point.  Unfortunately, the next step is where it all goes wrong.  In order to screed the concrete, 2-3 guys have to walk out into the middle of it. This drives the mesh, that was so carefully lifted, back down to the ground with every step. At best, this produces reinforcing that undulates up and down through your concrete (which is where the random cracking comes from imo).

The proof really shows itself when removing old concrete with mesh in it, however, most of the wwf is at the very bottom in partial contact with the soil. It does make it a pain in the butt to remove with all the tangled wire in it and it may even help to keep the slab from walking apart to some extent.

Rebar on the other hand, when installed correctly, remains in the concrete at proper elevation. In order to assure the location, intersections are tied with wire and plastic chairs are clipped underneath to hold height. Please don’t waste your money on wire mesh. For a little money, you gain big peace of mind.

In summary, rebar though more expensive is worth it. Rebar rules… wire mesh is for fools.                                 -Jon Molden, BST Concrete