Calculators/ Concrete/Concrete Pad Calculator
Concrete Pad Calculator
Concrete for shed, HVAC and hot tub pads.
Concrete Pad Calculator
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Equipment pads are small but carry concentrated point loads, so thickness matters more than area. Cured concrete weighs about 150 lb per cubic foot, which the sub-grade has to carry before anything is placed on top.
How this is calculated
- Volume = length × width × thickness ÷ 12.
- Four inches suits a shed or HVAC condenser. Hot tubs need six inches and often rebar, because a filled tub is a very heavy point load.
- Weight is volume × 150 lb, useful for checking whether the sub-grade needs compacting first.
Frequently asked questions
How thick should a hot tub pad be?
Six inches with rebar or mesh. A filled tub with occupants can exceed 5,000 lb concentrated on a small footprint.
Does a shed pad need a footing?
Not usually for a small shed on stable, well-drained ground. Larger structures and anything permanent normally need a thickened edge.