Short answer
For ideal conditions, the Concrete Masonry & Hardscapes Association (CMHA) lists a minimum aggregate base of 4 inches (100 mm) for pedestrian patios and walkways, 6 inches (150 mm) for residential driveways, and 8 inches (200 mm) for parking lots or residential streets. Streets and heavy-duty industrial pavements require qualified engineering rather than a universal minimum.
“Ideal” is doing important work.
CMHA describes ideal conditions as strong, structurally sound, well-draining subgrade in a stable, preferably non-freezing climate. If your site misses those conditions, the minimum may not be enough.
| Application | Ideal-condition minimum | Calculator use |
|---|---|---|
| Patio / walkway | 4 in (100 mm) | Available preset |
| Residential driveway | 6 in (150 mm) | Available preset |
| Parking / residential street | 8 in (200 mm) | Enter manually after review |
| Heavy duty / industrial | Professional design | Not a preset |
Four conditions that change depth
1. Subgrade strength
Soft, disturbed, clay-rich or poorly compacted soil can deform under a thin base. Site preparation and geotechnical conditions are outside a material-volume calculator.
2. Drainage
Water entering or trapped in the pavement section can weaken support and contribute to movement. A volume estimate cannot decide grading, drainage outlets or permeable-system details.
3. Freezing
Freeze-thaw exposure changes design requirements. CMHA advises increasing thickness when ideal non-freezing conditions do not exist; local practice and professional input matter.
4. Traffic load
A pedestrian patio and a vehicle driveway do not impose the same load. Commercial traffic, repeated trucks, streets and industrial work need project-specific pavement design.
Base depth is not excavation depth
Total excavation must make space for more than the aggregate base. A common planning stack is:
aggregate base + bedding course + paver thickness = layer-stack depth
That sum still does not include every grading, drainage or subgrade correction decision. The main paver base calculator displays the arithmetic stack so you can discuss it with the installer or supplier.
Keep the bedding course distinct
CMHA construction guidance separates compacted aggregate base from the bedding course. Manufacturer systems may specify a particular bedding material and depth. QUIKRETE’s patio data sheet, for example, describes 2–4 inches of compacted gravel or crushed rock plus 1–2 inches of its paver sand for that product system. Do not combine those layers into one density.
Depth decision checklist
- What traffic and maximum vehicle load will the surface carry?
- Is the subgrade strong and properly compacted?
- Where will water drain from the base?
- Does the location experience freezing?
- What base and bedding products does the selected paver system require?
- Does local code, a permit, designer or manufacturer require a different section?
Technical references
- CMHA — Proper Concrete Paver Base and Depth (2025)
- CMHA PAV-GSP-011-25 — Interlocking Concrete Pavers on an Aggregate Base
- CMHA PAV-TEC-002-22 — Construction of Interlocking Concrete Pavements
- QUIKRETE Patio Paver Sands data sheet
Scope
This guide summarizes public technical references for preliminary planning. It is not a site inspection, engineering design, manufacturer approval or local-code determination.