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Category Foundation Concrete

Slab Dimensions

Length (m)

Width (m)

Thickness (cm)

Reinforcement (Mesh)

Mesh Sheet Length (m)

Mesh Sheet Width (m)

Overlap Factor (%) Percent of area lost to overlapping sheets

Concrete Volume

0.00 m³

Total Slab Area

0.00 m²

Reinforcement Needs

        Mesh Sheets Needed
        0
        pcs
      

Total Mesh Area (w/ Overlap) 0.00 m²

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About

A slab-on-grade foundation is a structural engineering staple, commonly used in climates where the ground does not freeze or where the slab is insulated. It consists of a single layer of concrete poured several inches thick directly onto a prepared gravel bed. The integrity of such a slab depends heavily on two factors: the correct volume of concrete to achieve the design thickness and the proper reinforcement (usually welded wire mesh or rebar grid) to control shrinkage cracking and provide tensile strength.

This calculator is engineered for accuracy in ordering materials. It computes the precise concrete volume needed and, uniquely, calculates the number of reinforcing mesh sheets required, accounting for the industry-standard overlap. Overlap is critical; without it, the mesh sheets act as independent islands rather than a unified tensile system, compromising the slab's structural performance.

Formulas

The calculator determines the concrete volume based on slab dimensions. The reinforcement calculation accounts for the effective area of mesh sheets after subtracting the overlap required for structural continuity.

Vol_conc = L × W × T

To calculate the number of reinforcement mesh sheets:

N_sheets = ceil(Area_slabArea_sheet × (1 − %_overlap))

Reference Data

Mesh Type	Wire Gauge	Grid Spacing (in)	Weight (lbs/100 sq ft)	Common Usage
6x6 - W1.4xW1.4	10 ga	6 x 6	21	Light Residential, Patios
6x6 - W2.9xW2.9	6 ga	6 x 6	42	Standard Driveways, Garage Floors
6x6 - W4.0xW4.0	4 ga	6 x 6	58	Heavy Duty Slabs, Commercial
4x4 - W1.4xW1.4	10 ga	4 x 4	31	Pool Decks, Thin Overlays
4x4 - W2.9xW2.9	6 ga	4 x 4	62	High Traffic Walkways
4x4 - W4.0xW4.0	4 ga	4 x 4	85	Industrial Floors
Bar Mat #3	#3 Rebar	12 x 12	~75	Structural Foundations
Bar Mat #4	#4 Rebar	12 x 12	~135	Heavy Load Bearing Walls/Slabs

Frequently Asked Questions

The standard overlap for welded wire mesh is typically one square of the grid plus 2 inches, or roughly 6 to 8 inches (15-20 cm). In terms of area calculation, it is safe to assume a 10% to 15% loss of effective coverage area due to overlapping sheets.

Yes. It is standard practice to add 5% to 10% to your calculated concrete volume. This accounts for spillage, uneven subgrade depth, and material remaining in the pump or truck chute. This tool provides the exact geometric volume, so you should add your safety margin to the final figure.

No. Post-tension slabs use high-strength steel cables (tendons) that are tensioned after the concrete cures. This tool calculates volume correctly for any slab, but the reinforcement logic is specifically for passive reinforcement like rebar mesh or welded wire fabric.

Absolutely. For thicker slabs or heavier loads, rebar grids are preferred. While this tool calculates 'sheets' of mesh, you can approximate rebar needs by calculating the total length of bar required based on grid spacing (e.g., 12-inch on center), though the mesh overlap logic here is specific to sheet goods.

A floating slab is not anchored to deep frost footings. It 'floats' on the soil surface. This design requires careful reinforcement to ensure the entire slab moves as a rigid unit if the soil heaves, preventing cracks. Accurate mesh calculation is vital for this rigidity.