Shed Base Calculator
Calculate concrete, paving slabs and sub-base quantities for a rectangular garden shed base.
Typical use: Concrete shed bases, paving slab bases and sub-base preparation
Using this calculator
Open the interactive calculator to enter your project measurements and adjust the available settings. Review the calculated quantity and buying units before ordering materials. Check product coverage, pack sizes and installation guidance with the manufacturer or supplier.
Planning and practical guidance
How to Build a Shed Base: Concrete, Paving or Timber Options
Choose and prepare a firm, level shed base so the building remains square, supported and separated from persistent ground moisture.
- Check the shed manufacturer’s required base dimensions and support arrangement before preparing the site. Some floors need continuous support while others use bearers or a proprietary grid.
- Choose a site with practical access and drainage, allowing for roof overhang, door swing, maintenance access and nearby roots or vegetation.
- Mark the footprint and check it is square by measuring diagonals. A base that starts out of square can make shed panels, doors and roof sections difficult to assemble.
- For a concrete or paving base, remove soft topsoil and prepare a compacted sub-base appropriate to the ground and building size before the finished base layer is installed.