No, you do not need rebar for a 4- inch slab of concrete on grade. A 4-inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required .
You do not need rebar for any slab if you make it thick enough and space the joints properly. Rebar in jointed pavement is there to counter the cupping effect of thermal expansion. Originally Answered: Do you need rebar for 4 inch slab?
When I was writing we ran into the inquiry “When is rebar required for slabs?”.
Rebar is certainly required if the garage slab is 6 ” or thicker. This is the short & sweet answer. Rebars cost money, both in material and labor cost.
Slabs thicker than 5 ” should have a web of rebar to prevent it from cracking. Patios near buildings commonly bridge backfilled ground and should have added tensile strength, as should those on slopes or weak ground. Small concrete slab, walkway, and concrete driveway are a couple more items to keep in mind.
The choice between rebar or wire mesh often depends on the strength desired in the end product. Some contractors prefer to use both in their concrete slabs – rebar between the 1/2 and upper 1/3rd and mesh between the upper 1/3rd and 1/4 of a 4” thick pad.
Convert your longitude measurement into inches: 15 feet x 12 inches per foot = 180 inches. Divide your result by the spacing measurement: 180 in / 14 in = 12.87 (round up to 13)Add one rebar to your result: 13 + 1 = 14.
Why put rebar in concrete?
Why Rebar Spacing is Crucial. Grade of steel;Size and spacing of the steel reinforcing; and. Location of the steel within the product.
This of course begs the inquiry “Why does concrete need metal rebar?”
Concrete is made by mixing cement, sand and aggregate stone with water. Some more ideas to think about: types of rebar, understanding rebar, rebar provides additional tensile strength to a concrete structure, the thickness of concrete, rebar sizes, rebar positioning, base material, compressive vs tensile strength, and wire mesh vs rebar.
Do you need reinforcing mesh in your concrete slab?
Some locations require reinforcement no matter the size or scale of the concrete. This is especially true of certain public buildings. The main slabs that require the steel reinforcing mesh will be those that expect a heavy workload. Anything from a lot of foot traffic, walls, or other foundational pieces will need that extra strength.