Open-graded base for pavers — what it is, when it wins, and why it's catching on.
The new-school paver base spec — single-size clean stone that lets water percolate through instead of shed off. Here's what open-graded is, the exact three-layer stack, and the decision framework for when it beats traditional ABC.
What open-graded base is
- Single-size clean stone with no fines (no dust, no fill).
- 3-layer stack: 6–12" #57 stone base → 4" #4 stone leveling → 2" #8 setting layer.
- Non-woven geotextile between subgrade and base.
- Gaps between stones = free water flow (percolation).
- No compaction cycles required — stones lock mechanically.
When open-graded wins
- Permeable paver systems (Aqualine, Eco-Priora, Turfstone).
- Sites with existing drainage or pooling problems.
- Stormwater-credit projects (HOA or municipal).
- Expansive-clay subgrade needing decoupled base.
- Projects targeting LEED or Green Build credit.
When traditional ABC still wins
- Standard non-permeable pavers on well-drained sites.
- Decomposed-granite subgrade with natural drainage.
- Cost-sensitive projects with no drainage concern.
- Tight-budget driveways where fine-graded compaction is proven adequate.
Why open-graded is gaining share
- ICPI updated commercial paver specs emphasize open-graded systems.
- Municipal stormwater rules credit permeable pavers against impervious-area limits.
- Install crews report faster placement (no compaction cycles) and easier leveling.
- Homeowner benefit: real drainage performance, no monsoon pooling.
AE's open-graded install spec
- Non-woven geotextile over stabilized subgrade.
- 6–12" #57 clean stone base (depth per traffic load).
- 4" #4 clean stone leveling layer.
- 2" #8 chip setting layer, screeded flat.
- Pavers set directly on #8 layer.
- Joint fill: #8 clean stone for permeable systems, polymeric sand for standard pavers on open-graded base.
- Robust edge restraint (spiked aluminum or concrete curb).
- 3-year AE workmanship warranty.
For a residential patio typically 12–16" total: #57 (6–12") + #4 (4") + #8 (2") + pavers. Driveways go deeper per traffic load.
Firm any soft native soil and cut a minimum 1/8" per foot fall away from structures so percolated water still exits laterally.
Non-woven geotextile (not woven) separates the clean stone base from native fines that would otherwise migrate up and clog the voids.
Dump 3/4" #57 stone across the fabric. Because there are no fines, no compaction cycles are needed — the stones lock mechanically as they land.
Rake and screed the #57 to a level plane. Add lifts as needed to build up to spec depth without disturbing the fabric below.
6" for standard residential permeable patios, 8–10" for pedestrian-plus-cart traffic, 10–12" for driveways per ICPI open-graded spec.
1.5" #4 stone goes on top of the #57 as the leveling layer. Spread and rake evenly — same no-compaction rule applies.
Pull a straight edge across the #4 layer to confirm plane. Correct any high spots before the setting layer goes on.
3/8" #8 chip is the setting course pavers sit on. Dump, rake, and prepare to screed to exact final grade minus paver thickness.
Set 1" screed rails (or dedicated open-graded screed pipes), screed the #8 chip to plane, then remove rails and fill their voids.
For permeable pavers, fill joints with clean #8 chip. For standard pavers on open-graded base, sweep and activate polymeric joint sand.
Common questions.
Considering open-graded base for a drainage-critical project?
AE will assess your site drainage, subgrade, and stormwater requirements — and quote both open-graded and traditional ABC options head-to-head so you can decide.
Start My Project PlanWhy this is an investment, not a cost.
An AE backyard is engineered to add daily livability and long-term home value. We publish honest ranges and build to code with a licensed and bonded Arizona crew. AE provides project-specific workmanship and manufacturer-warranty information in the signed agreement. Website summaries are for planning only.
- Licensed, bonded & insured in Arizona. ROC 340966 (R-62) · ROC 341002 (R-3) · ROC 347738 (KA-5) · ROC 211530 (CR-21). Most Arizona contracting work valued at $1,000 or more — or requiring a permit — must be performed by a properly licensed contractor, subject to statutory exemptions. Verify the legal entity, license status, and classification with the Arizona Registrar of Contractors.
- Real ranges, itemized scope. You see materials, finishes, equipment models, and a line-item budget before you sign — not a one-line "pool — $90,000."
Related base-science reading
More open-graded questions?
Stormwater credit, subgrade prep, and open-graded vs ABC cost — in the Hardscape section of the Homeowner FAQ.