Material comparison
Paver base materials in Arizona — ABC, sand, and drainage, compared
Nobody shops for base material. It is buried the day after it goes in, and it is also the single biggest reason one patio still looks laid-straight in year ten and the neighbor's is wavy by year three. Here is what actually goes under an Arizona paver field, what each layer does, and how Valley soil and monsoon runoff change the plan.
The honest version: The paver you pick is a style decision. The base, bedding course, joint sand, edge restraint, and drainage are the durability decision. If a bid does not name the base material and compacted depth, you are not comparing the same job.
- AZ ROC 211530 · 347738 · 341002 · 340966
- Arizona-built since 2005
- President, Southwest Hardscapes Association
01
The layers, compared
| Material | What it does | Arizona note |
|---|---|---|
| ABC (aggregate base course) | The structural base. Compacted in lifts under every paver field AE installs. | 2–3" on patios and walkways, 4–6" on driveways, with additional ABC for build-up or higher traffic. Graded aggregate compacts and locks; it carries the load, not the sand. |
| Quarter minus | Not a paver base. Used as a turf base only. | Quarter minus is never used under pavers on an AE install. It is a fines-heavy material that behaves very differently under a unit-paver field than a graded base course. |
| Bedding sand (1" course) | The screeded setting course the pavers are laid into — a leveling layer, not a structural one. | 1" screeded and left undisturbed on every install. Thicker sand is not a shortcut for missing base depth; it is the most common reason a field goes wavy later. |
| Polymeric joint sand | Swept into the joints and activated with water so the field interlocks. | Used on every AE paver install. Joint sand is what keeps units working together instead of individually; it also resists washout in monsoon runoff. |
| Concrete / mortar-set detail | Specified for certain natural-stone selections or specific conditions. | Called out in the written scope when the selection or condition requires it — not a default swap for a compacted-aggregate base. |
| Native soil (subgrade) | What everything above sits on. It gets prepped, not ignored. | Valley subgrades range from caliche layers to expansive clay to loose sandy fill. Excavation depth, moisture, and compaction are decided on site. |
This is the AE standard install spec. Final excavation depth, base thickness, and any drainage structures are set by the measured site conditions and the signed scope for your project.
02
AE's standard base spec
- 2–3" compacted ABC under patios and walkways.
- 4–6" compacted ABC under driveways, plus additional ABC for build-up or higher-traffic conditions.
- 1" screeded bedding sand course, left undisturbed before laying.
- Polymeric joint sand swept and activated on every install.
- Quarter minus is never used under pavers — it is a turf base material only.
- Edge restraint chosen for the adjacent condition, with grade and drainage planned for the site.
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03
What Arizona soil does to the plan
- Caliche: a hard cemented layer that changes excavation and how water moves below the field.
- Expansive clay: moves with moisture, so moisture control and drainage matter as much as depth.
- Loose sandy fill and old backfill near foundations: needs prep and compaction before any base goes down.
- Existing irrigation and drainage lines: located before excavation, and worked into the grade plan.
- Slope from the house: every field is graded to move water away from the structure on purpose.
04
Drainage details that belong in the scope
- Planned slope and where the water is being sent — not just "away from the house."
- Channel drains or area drains where the yard has nowhere else to shed volume.
- Outlet location, so a drain empties somewhere useful instead of into a low spot.
- Transitions at turf, planters, and pool decks, where two surfaces meet at different elevations.
- Edge restraint at open edges, so joint sand and base do not migrate during heavy runoff.
05
Common shortcuts to watch for on a bid
- A thick sand bed substituting for missing base depth.
- Quarter minus, road base of unstated grade, or "fill" listed instead of a compacted ABC depth.
- Regular masonry sand in the joints instead of polymeric joint sand.
- No edge restraint line item on a field with open edges.
- No excavation depth, no haul-off, and no drainage plan anywhere in the proposal.
06
How AE handles it
We confirm subgrade conditions on site, set excavation and compacted base depth for the actual use of the surface, and write the base material, bedding course, joint sand, edge restraint, and drainage plan into the proposal so you can compare it line for line. Installs carry the AE workmanship warranty; manufacturer coverage on the paver product is controlled by that manufacturer's terms.
FAQ
Common questions.
AE's standard is 2–3 inches of compacted ABC under patios and walkways and 4–6 inches under driveways, with additional ABC where build-up or higher traffic calls for it. On top of that goes a 1-inch bedding sand course and polymeric joint sand in the joints. Poor subgrade, heavy vehicle loads, or a large build-up can push the base deeper — that gets decided on site, not guessed from a template.
Not on an AE install. Quarter minus is a turf base material. Under pavers we use graded ABC compacted in lifts, because that is what carries the load and holds elevation over time. If a bid lists quarter minus under a paver field, ask the contractor to put the base material and depth in writing before you sign.
Bedding sand is the 1-inch screeded setting course the pavers are laid into — it levels units, it does not carry structure. Polymeric joint sand is swept into the joints after laying and activated with water so the field interlocks and resists washout. They are different products doing different jobs, and both are on every AE paver install.
It can. Caliche is a hard cemented layer common in Valley soils, and it changes how the area is excavated and how water moves below the surface. Where we hit it, the excavation approach and any drainage detail get adjusted on site. Caliche is one of the reasons the base plan is confirmed at the project, not assumed from a spec sheet.
Monsoon rain arrives fast and in volume, so the field has to shed water somewhere on purpose. That means planned slope away from the structure, edge restraint suited to the adjacent condition, and — where the site calls for it — drains, channel drains, or a routed outlet included in the scope. A flat field with nowhere for water to go is a maintenance problem regardless of how good the base is.
No — an overlay is a different detail. When pavers go over sound existing concrete, the slab is the base, and the assembly is a bedding course plus the paver field with drainage and edge conditions worked out for the slab's slope and elevation. The slab has to be evaluated first; overlays are not automatically the right call on failing or badly graded concrete.
Base material and compacted depth, bedding sand thickness, joint sand type, edge restraint, excavation depth and haul-off, and the drainage plan. Those line items are where two bids that look the same on price actually differ. Ask for them in writing — and get the workmanship warranty terms in writing separately from any manufacturer coverage.
Want the base spec on your project in writing?
Send photos and rough dimensions and we'll put excavation, base depth, bedding course, joint sand, and drainage on the proposal in plain language — so any bid you compare it against has to show the same.
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Why 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."
Next step
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Homeowner FAQ
More base questions?
Base depth, drainage, and joint sand questions are answered in the Hardscape section of the Homeowner FAQ.