The standard build, layer by layer
| Layer | Material | Thickness |
|---|---|---|
| Subgrade | native soil, crowned & compacted | — |
| Separation | woven geotextile | one sheet |
| Base | crusher run / QP / Item 4 (with fines) | 4–8 in compacted |
| Surface | #57 stone (¾ in clean) | 2–3 in |
Choosing your base thickness
- 4 inches base (6 in total): sandy/gravelly well-drained soil, passenger vehicles, moderate climate. The default residential build.
- 6 inches base (8 in total): clay or silty soil, frost-heave regions, occasional trucks or trailers. The safe default if you're not sure.
- 8–12 inches base: heavy vehicles, long slopes, wet spots, or commercial use.
Why two layers? Crusher run's fines make it pack like asphalt — perfect structural base, ugly and dusty surface. Clean #57 drains instantly and looks crisp, but rolls and ruts if used thick. Two thin jobs done by two right stones.
Frost and drainage rules
In freeze-thaw climates the base acts like a roof over the subgrade: crown the driveway ½ inch per foot of width (center higher than edges) so water sheets off, never pools, and extend the base past the planned edges by 6–12 inches — edges are where driveways unravel first.
Worked tonnage examples
- 50 × 12 ft lane, standard 6 in total: 600 ft² × 6/12 ÷ 27 = 11.1 yd³ ≈ 14.6 tons (11.1 base + 3.5 surface).
- Same lane on clay, 8 in total: ≈ 19.5 tons.
- Turnaround pad 20 × 20 ft at 6 in: 400 ft² → ≈ 9.7 tons.
Run your own numbers with both layers at once in the gravel driveway calculator.