Useful when somebody has a nice surface price in mind but still has no clue what the base layers will actually need.
Block paving
Sub-base: 16.5 tonnes
Bedding: 4.4 tonnes
Geotextile: 55 m²
50 m² of block paving build-up at 150 mm sub-base depth needs roughly 16.5 tonnes of sub-base before compaction losses and tidy-up.
Use this before you let a contractor blur base depth, edge restraint and drainage extras into one vague price.