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Sand Sub-Base Calculator
Work out sharp sand and sub-base aggregate for paving foundations.
How We Calculate This
This calculator estimates MOT Type 1 sub-base aggregate and sharp sand for paving foundations.
Sub-base
Tonnes = Area × Depth × Density. Compacted MOT Type 1 density is ~1,950 kg/m³ (loose/delivered material is nearer 1,500, so allow for compaction). Lay and compact in ~50mm layers.
Sharp sand
The sand blinding layer sits on top of the sub-base. Typically 30-50mm deep, screeded level as the final bed for slabs. Sharp sand density is ~1,600 kg/m³ air-dry (heavier when damp).
Membrane
On soft or clay ground, lay a permeable geotextile membrane across the whole excavated area beneath the sub-base to stop the aggregate sinking into the subsoil. A weed membrane can also sit just under the paving to suppress weeds through the joints. Allow 10% extra for overlaps (overlap sheets by at least 300mm).
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.