Effective Concrete Slab Width for a Concentrated Load

The Nature of Concrete

• While concrete is one of the most durable materials used in construction around the world, it still has its limits. If the proper mixing methods as well as the curing time and reinforcement measures are not followed, the slab will crack out. Too much weight is one of the issues that can make a concrete slab crack, and if you are planning on having a concentrated load you will need to work together with a structural engineer to determine the exact width of your project’s slab.

Importance of Footers

• Most concrete structures that are expected to carry a lot of concentrated weight will utilize what is known as a footer. The footer is not part of the actual slab itself, or the slab thickness, but it is nevertheless concrete and goes underneath the slab itself. The footer is usually placed on the outer edges of a slab to help spread out the weight so that the slab doesn’t shear off where concentrated loads are placed on the outer edges, such as with foundation walls on top of a slab floor. The footers also help the edges from sinking too rapidly into the soil from the concentrated weight.

Average Slab Width

• The average reinforced slab is usually between 4 and 6 inches, and is used in sidewalks, basement floors, porch slabs and other areas. However, in cases such as basements and porches, the concentrated weight is usually spread out along the outer edges of the slab where it is also spread out into the footers below the slab. For concentrated loads that are focused in one specific area, more concrete is needed.

Heavy Load Width

• For heavy loads, the minimum is usually around 8 inches to be on the safe side, such as with driveways or garage slabs that need to accommodate a vehicle. Commercial vehicle bays, on the other hand, need an even thicker slab, going to 12 inches or beyond depending on the situation. Steel reinforcement is needed in these cases, as the concrete itself cannot take the pressure of the concentrated load alone. A structural engineer can help determine the exact specifications depending on the expected load.