How to Determine Concrete Slab Requirements

Always choose the maximum reinforcement available for concrete when building a foundation slab. The minimum thickness of the slab must be at least 4 to 5 inches, with a strength of 3,000 pounds per square inch for residential homes. In many locations, an additional 6- to 8-inch-wide footer that reaches below the normal frost line is required. Larger slabs certainly need steel reinforcement in the form of rebar or wire mesh on 4-foot grids.

Select a minimum of 4-inch-thick concrete with a strength of 4,000 psi for driveways sustaining normal weight traffic, such as regular sized cars and trucks. Driveways needing to accommodate larger vehicles, such as oversize trucks or recreational vehicles may require 5-inch-thick concrete to adhere to local building codes. Reinforcing driveways with steel rebar or wire mesh on 4-foot grids will reduce the risk of excessive cracking that may damage the driveway surface. Single-vehicle driveways are commonly 8 to 9 feet wide, while double drives usually range from 15 to 18 feet in width.

Opt for a thinner 3- to 3 1/2-inch thickness of concrete for sidewalks and residential patios. Going thinner than this, however, may cause the concrete to crack or break under regular foot traffic. Fiber mesh is an excellent alternative for reinforcing concrete for this type of project. Steel reinforcement, although not generally required for small-scale projects, can certainly help reduce the incidence of serious cracking.