The size of rebar you need for a concrete slab is determined by local and state building codes. Rebar is the reinforced metal bar that is placed in a concrete slab for extra stability and strength.
Building Codes and Rebar Size
Building codes will help you determine the length and size of rebar you need to use for the concrete slab you are pouring. Many building codes can be found online under the building department section of your local municipality. If you are unable to find this information online, contact your local building department or look for this information on your state website.
Look up the size of slab you intend to pour and the required rebar size should be outlined. If there are two conflicting measurements between the state and local requirements, use the larger rebar measurement size. You can also contact your local building department representative and point out the difference between the two codes and ask for instructions. This may be the best alternative, particularly if you need to have building inspector approval for permits and to move forward on your project.