Landscaping & Groundworks Calculators

Landscaping and groundworks form the foundation of any outdoor building project in the UK, from laying a new driveway or patio to installing drainage systems and garden boundaries. Accurate material quantities are essential when ordering bulk materials like aggregates, topsoil, and gravel, because over-ordering wastes money and under-ordering delays the job.

For driveways and patios, the standard UK construction method involves a compacted Type 1 MOT sub-base (typically 100–150mm deep), followed by a sharp sand laying course and the chosen surface material. Our Type 1 sub-base calculator works out exactly how many tonnes you need to order. Type 1 is crushed limestone or granite graded to the Department for Transport's Specification for Highway Works (Series 800) and is available from any UK builders' merchant or aggregate supplier.

Drainage is a critical aspect of UK groundworks, particularly given the country's rainfall levels. Under Approved Document H of the Building Regulations, surface water must be managed on-site where possible, with soakaways designed to BRE Digest 365 standards. Our soakaway sizing calculator helps you size a soakaway crate or gravel-filled pit based on your roof area and local soil percolation rate. For properties where soakaways are not feasible (clay soils, high water tables), French drains and linear drainage channels provide alternative solutions.

Decking has become hugely popular in UK gardens, with both softwood (pressure-treated pine) and composite options available. Standard UK decking boards are 32mm × 150mm and come in lengths of 2.4m, 3.0m, 3.6m, and 4.8m. Composite decking from brands like Millboard, Trex, and TimberTech offers low-maintenance alternatives at a higher price point. Our decking calculator estimates boards, joists, fixings, and all materials needed for your deck area.

Bulk materials like topsoil, gravel, sand, and bark mulch are typically delivered in bulk bags (approximately 850kg each) or loose loads measured in tonnes. Ordering by the tonne is almost always cheaper than buying 25kg bags from a DIY store. For any project requiring more than half a tonne of material, it is worth getting a delivered price from a local aggregate supplier. Our landscaping calculators convert between volume (m³) and weight (tonnes) using accurate UK material densities, so you can order confidently.