Pavers sit on 1 in (25 mm) of concrete sand over a base of compacted crushed stone. CMHA, the industry body that took over from ICPI, sets the base at 4 in (10 cm) or more after compaction for patios, walks and other areas people walk on, and 6 in (15 cm) or more for driveways, on well-drained soil. With 2⅜ in pavers, you dig about 7⅜ in for a patio and 9⅜ in for a driveway. Wet, weak or frost-prone soils need a thicker base.
How deep should a paver base be?
| Use | CMHA minimum base | This Old House | Dig, with 2⅜ in pavers |
|---|---|---|---|
| Patio, walk, pedestrian area | 4 in compacted | 4–6 in | 7⅜ in |
| Residential driveway | 6 in compacted | 6–8 in | 9⅜ in |
CMHA Tech Note PAV-TEC-002 gives the minimums for well-drained soils and 2⅜ in (60 mm) pavers for both uses. The dig depth is our sum of paver, 1 in of sand and the base; This Old House digs 6 to 8 in for pedestrian areas and 8 to 12 in for driveways.
The minimums are for soil that drains. CMHA says colder climates and soils that stay wet or are weak need a thicker base, and This Old House’s landscape contractor dug out a foot of loam to reach firm subsoil before he started building up the base. If the ground under your patio is soft, wet or full of roots, that is where the extra depth goes.
What to use for the base
- The base: crushed stone with fines, a dense-graded aggregate that packs hard, the same kind your state transportation department specifies for road base. CMHA says to use local base specifications where they exist. For walks and patios, it allows base made entirely of recycled crushed concrete, though that can bring white efflorescence onto the pavers.
- The bedding sand: washed concrete sand (ASTM C33), not stone dust, screenings or mason sand, which CMHA says compact unevenly and keep water from draining sideways.
- Fabric, sometimes: CMHA lists geotextile as optional, for soil that stays saturated part of the year, freezes and thaws, or is clay or moist silt. It goes on the compacted soil under the base.
How to compact it
- The soil first: compact the dug-out subgrade. CMHA asks for at least 98% of standard Proctor density, the lab test for how tight a soil can pack.
- The base in layers: spread and compact it in 4 to 6 in lifts with a 7,000 lbf reversible plate compactor, or thinner lifts with a 5,000 lbf machine (CMHA). This Old House’s contractor lays it in 3 in layers. Compact it damp, at what CMHA calls its optimum moisture, to 98% of standard Proctor for patios and driveways.
- Make it flat before the sand: CMHA wants the finished base within ⅜ in of a 10 ft straightedge. Sand isn’t for filling dips: they come back through the pavers.
- Slope it: at least 1.5% (CMHA); This Old House uses 1 in for every 4 ft, about 2%, away from the house.
For a low spot that stays wet, CMHA runs a 4 in perforated drain pipe in at least 3 in of No. 57 stone, wrapped in geotextile, along the edge of the paving, with its top even with the compacted soil.
Questions people ask
How deep should a paver base be?
At least 4 in compacted for patios and walks, 6 in for driveways, on well-drained soil (CMHA). Wet, weak or cold-climate soils need more.
How deep do I dig for pavers?
The paver thickness, plus 1 in of sand, plus the base: 7⅜ in for a patio with 2⅜ in pavers and 4 in of base, 9⅜ in for a driveway.
What gravel is best for a paver base?
Crushed stone with fines that compacts hard, the road base your state specifies. Round stone such as pea gravel doesn’t lock together; the federal gravel roads manual notes that rounded particles shift under loads.
Can I use stone dust instead of sand under pavers?
CMHA says no: screenings and stone dust compact unevenly and slow drainage. Use washed concrete sand, 1 in thick.
How much paver base do I need?
Area × compacted depth, plus about a third for compaction. A 120 sq ft patio with 4 in of base takes about 2 cu yd of loose base, 3.2 tons; the paver calculator works it out.
Sources
- Concrete Masonry & Hardscapes Association (formerly ICPI), Tech Note PAV-TEC-002, Construction of Interlocking Concrete Pavements
- This Old House, How to install pavers
- Skorseth and Selim, Gravel Roads Maintenance and Design Manual, South Dakota LTAP for the Federal Highway Administration (copy hosted by the EPA)
- Penn State Center for Dirt and Gravel Road Studies, Driving Surface Aggregate tech bulletin (spread a third more than the compacted depth; 1.62 tons per loose cubic yard)
Checked October 12, 2026. Metric values are converted. Dig depths are our arithmetic.