There is no single paver-base depth that fits every patio. The general guide hosted by Oregon State Extension uses a 4-6-inch base in its excavation example, then says thickness depends on the supporting material and load.1 Confirm the selected paving system, soil, drainage, frost and use before treating a depth chart as a design. This page compares cited guidance and calculates quantities for chosen depths.
What the sources say
| Source | Base/depth guidance | Scope and limit |
|---|---|---|
| 10-Step Guide hosted by Oregon State Extension1 | 4-6 in base in excavation example; thicker for soft clay or driven-on paving | General guide; explicitly directs the reader to supplier recommendations |
| Rochester guide hosted by Mid-Atlantic Concrete Products2 | 4-6 in compacted base for pedestrian traffic; 8-12 in for light vehicles | Guide scenarios tied to soil/drainage conditions, not approval for every site |
| CMHA/ICPI aggregate-base guide specification3 | Nominal 1 in screeded bedding sand; correct base deficiencies before paving | Interlocking concrete pavers on aggregate base; the document requires project-specific choices |
Do not combine the lowest numbers from different sources into one approved section. The Mid-Atlantic-hosted guide also illustrates 6-12 inches in its typical cross-section while its table distinguishes pedestrian and vehicular ranges.2 Read the selected system’s full section and conditions rather than using the picture alone.
Base, bedding and excavation are different
Compacted base is the specified installed aggregate layer. Bedding sand is the thin selected layer immediately below the pavers. Paver thickness is a separate product dimension. Soil below the section is the subgrade. Joint sand is between pavers, not an extra full-area bedding layer.
Section thickness = specified compacted base + specified bedding layer + paver thickness. Actual excavation follows the required finished elevations and site grade. Do not add loose delivered depth to the finished section or treat a section-thickness sum as the depth below uneven existing ground at every point.
Quantity formula
Installed base cu yd = actual base footprint (sq ft) × selected compacted depth (in) / 324. Use the base footprint, which may extend beyond the pavers under the selected design. Calculate bedding on its own footprint and depth. An installed quantity is not automatically the volume of loose material to order.
Ask the supplier or project designer for the material-specific loose-to-compacted conversion and any separate handling allowance. Do not automatically add one percentage for both. Use a density matched to the same material and volume state if converting to weight. Confirm the supplier’s sales increments before rounding.
Depth sensitivity for a 144-sq-ft base footprint
Calculated quantities only. These depths are scenarios, not recommendations. No loose-volume conversion, allowance or supplier rounding.
| Selected compacted depth | Installed cu ft | Installed cu yd |
|---|---|---|
| 4 in | 48 | 1.777778 |
| 5 in | 60 | 2.222222 |
| 6 in | 72 | 2.666667 |
| 8 in | 96 | 3.555556 |
| 10 in | 120 | 4.444444 |
| 12 in | 144 | 5.333333 |
Three checked examples
1. A chosen 4-inch base
For an actual base footprint of 12 × 12 = 144 sq ft, installed quantity = 144 × 4 / 12 = 48 cu ft, or 1.777778 cu yd. Selected 1-inch bedding over the same area is 12 cu ft, or 0.444444 cu yd. Neither figure establishes the loose delivery quantity or a suitable design.
2. A selected 6-inch base with a wider footprint
Suppose the project specifies a base footprint 6 inches beyond every side of a 12 × 12-foot paved area. This is a hypothetical design input, not a source-mandated extension. Base area = 13 × 13 = 169 sq ft. At 6 inches compacted: 84.5 cu ft, or 3.129630 cu yd. If bedding covers only the 144-sq-ft paving footprint, calculate it separately; do not enlarge every layer automatically.
3. Section thickness and slope math
With selected 6-inch compacted base, selected 1-inch bedding and a 2⅜-inch paver, the arithmetic section sum is 9⅜ inches. Compaction/finished-height details still need to match the actual installation specification; the supplier guide’s excavation table uses rounded depths and includes a compaction adjustment.2
The OSU-hosted guide gives 1 inch of fall per 4 feet (1/4 in/ft), while the Mid-Atlantic-hosted guide gives about 1 inch per 8 feet (1/8 in/ft).1, 2 Over a 12-foot run, those calculate to 3 inches and 1.5 inches respectively. They are different source recommendations, not interchangeable defaults. Resolve the actual drainage direction, slope and elevations for the project rather than silently choosing one.
Do not repair the base with extra sand
The OSU-hosted guide describes spreading 1-1.5 inches of sand and screeding over 1-inch rails to obtain a uniform 1-inch layer.1 That spreading step is not a 1.5-inch finished bedding specification. The CMHA/ICPI guide calls for nominal 1-inch screeded bedding and says not to fill base depressions with bedding sand.3
Compaction equipment and lift thickness depend on material and project requirements. The OSU-hosted suggestion to divide aggregate into three smaller layers is that guide’s method, not proof that three lifts suit every depth and material.1 Check the actual base and equipment instructions rather than guessing a lift count.
Before digging or ordering
- Resolve the actual paving system, intended traffic, soil, drainage, frost and any project/local requirements.
- Confirm finished elevations, slope and discharge route. Do not direct runoff toward a structure by copying a diagram.
- List each layer’s footprint and specified installed thickness separately.
- Confirm aggregate specification, compaction/lift requirements, loose-volume conversion, density and separate allowance.
- Use the relevant local utility-location process before excavation; this page does not establish clearance to dig.
FAQ
Is a 4-inch base enough?
The cited guides include 4 inches in some scenarios but do not establish it as enough for your soil, load or climate. Resolve the section for the actual project.
Is base volume the same as gravel to order?
No. The chart calculates installed compacted geometry. Delivered loose quantity depends on the selected material and a verified conversion, with allowance and sales rounding handled separately.
Should I use 1 or 1.5 inches of bedding sand?
The OSU-hosted 1-1.5-inch spreading step is screeded to 1 inch. The CMHA/ICPI guide also calls for nominal 1-inch screeded bedding for its system. Follow the selected system, not a stripped-out spreading number.
Which slope should I copy?
The two guides give different slope examples. The arithmetic comparison above does not select the appropriate drainage design. Confirm the actual project elevations and requirements.
Related quantity tools
Paver base calculator | Bedding and joint sand guide | Paver coverage guide | Square footage calculator
Sources
- 10-Step Guide to Installing Pavers, hosted by Oregon State Extension (general base, sand and slope guidance; thickness depends on support and load)
- Rochester Paver Install Guide, hosted by Mid-Atlantic Concrete Products (traffic-specific base scenarios, typical section and different slope example)
- CMHA/ICPI: Pavers on Aggregate Base (system-scoped screeded bedding and base-deficiency guidance)