Over-excavation, spillage and uneven subgrade. 5-10% for formed work, 10-15% on rough ground.
Loose aggregate loses volume when it is rolled. Order the loose volume, not the finished volume.
Optional. Leave at zero to skip the cost estimate.
Material quantity estimate for planning and purchasing. Not structural engineering advice, not a bid, and not a code determination.
How deep does a paver base need to be?
Base depth is set by what drives on it, and by how well your soil drains. The sand layer is always 1 inch — that one is not a judgement call.
| Use | Base stone | Bedding sand |
|---|---|---|
| Walkway, patio (foot traffic) | 4 in | 1 in |
| Patio on clay or poor drainage | 6 in | 1 in |
| Driveway, vehicle traffic | 8-12 in | 1 in |
| Cold climate, frost-susceptible soil | 8-10 in | 1 in |
The one inch sand rule
The bedding sand is not included in the figure above, because sand and crushed stone have different densities and come off different piles. Work it out on the sand calculator at a 1 inch depth — for a 20 x 12 ft patio that is 20 ft³, or about 0.75 cubic yards.
And it is exactly 1 inch, screeded flat, never compacted before the pavers are set. Thicker sand is the single most common cause of a paver patio going wavy: sand is not a structural layer, and any more than an inch of it will consolidate unevenly under load.
Use coarse, angular concrete sand (ASTM C33) rather than fine play or mason sand. Round grains roll, angular grains lock.
Excavation depth
Total excavation is base + sand + paver thickness. For a standard patio that is 4 + 1 + 2.375 = about 7.5 inches below the finished surface. Slope the excavation away from the house at a minimum of 1/8 inch per foot — 1/4 inch per foot is better — and carry that slope through every layer rather than trying to correct it in the sand.
Dig 6-8 inches wider than the paver field on all sides so you have room to set edge restraint into the compacted base.
Common questions
How much gravel do I need under pavers?
Four inches of compacted crushed stone for a patio or walkway, 6 inches on clay, and 8-12 inches for a driveway. A 20 x 12 ft patio at 4 inches needs about 3.7 loose cubic yards once you allow 25% for compaction, which is roughly 5.4 tons.
How thick should the sand under pavers be?
One inch, screeded and left uncompacted until the pavers are laid. Thicker sand consolidates unevenly and is the usual reason a patio goes wavy in its first year.
Can I use paver base panels instead of gravel?
For light foot-traffic patios on stable, well-drained soil, the foam panel systems work and save a lot of excavation. They are not a substitute for a compacted stone base under vehicles or on soil that heaves.