Paver Base Materials: What Goes Under Your Patio

The best base for pavers is compacted, crushed angular stone, usually a dense-graded aggregate (3/4 inch down to fine particles) or an open-graded 3/4 inch clean stone known as ASTM No. 57, topped with about 1 inch of bedding sand. Pavers get the credit, but the base does the work. It carries the load, sheds water and keeps the surface flat for decades. Below, we explain each material, what each layer does and how soil, drainage and traffic change the choice.

TL;DR

• Use crushed, angular stone for the base, not rounded pea gravel, and compact it in thin lifts.
• Dense-graded base gives stability. Open-graded No. 57 stone gives drainage. Many jobs call for one or the other, chosen by soil and water.
• Bedding sand is a thin leveling layer of about 1 inch. It is not a way to fix a poor base.
• Base depth depends on traffic, soil and climate. Walkways and patios need less than driveways, and wet or weak soil needs more.
• Slope away from the house and compaction matter as much as the material you buy.

Table of Contents

• The layers under a paver patio, from the ground up
• Crushed stone: the standard base material
• Dense-graded vs. open-graded base
• Bedding sand and joint sand
• Other base options and when they fit
• How thick should the base be?
• Compaction and slope matter as much as the material
• Common mistakes in paver base work
• Our perspective
• Plan your paver project with us
• FAQ
• Sources

The layers under a paver patio, from the ground up

A paver surface is a system of four parts. Each has a different job, and skipping one is where most failures start.

1. Subgrade. This is the native soil, excavated and compacted. Everything above it can only be as stable as this layer.
2. Aggregate base. Crushed stone or gravel sits on the subsoil and provides support, stability and drainage.
3. Bedding layer. Usually coarse sand or small chip stone, typically about 1 inch thick, giving the pavers a smooth, even surface to sit on, according to the same paver manufacturer guidance.
4. Pavers and joint sand. The pavers are locked in place by the sand swept into the joints and by edge restraints around the perimeter.

If you want a deeper walk through depths and quantities, our guide to paver base depth and ordering math covers the numbers.

Crushed stone: the standard base material

For most U.S. patios and walkways, crushed stone is the default. Suppliers sell it under several names, and that is where homeowners get confused. One industry guide notes that well-graded crushed aggregate may be sold as road base, crusher run, dense-graded aggregate or crushed stone with fines.

The common thread is angular stone with a range of sizes. The sharp faces interlock when compacted, and the fine particles fill the voids so the layer becomes dense and firm. Rounded gravel, such as pea gravel, never locks together and keeps shifting under foot traffic.

What to ask a supplier for:

• Crushed, angular stone, not river rock.
• A graded blend from about 3/4 inch down to dust for a dense-graded base.
• Aggregate that the local state department of transportation approves for road base. The Concrete Masonry & Hardscapes Association says such aggregates are appropriate for interlocking concrete pavements and available from most quarries.

In Central Arkansas, local quarries supply crushed limestone and similar products, and your installer should know which blend suits your site. We source and compact base material on every paver job, and our crews match the product to the soil conditions we find once the excavation is open.

Dense-graded vs. open-graded base

There are two main families of aggregate base, and the right one depends on water.

The Polycor base guide explains that open-graded base is valuable in wet climates or poor drainage, while dense-graded base provides load-bearing capacity and stability. Its low-fines structure also resists freeze-thaw damage, because water passes through instead of collecting in the base.

A note on fines for vehicle areas

Iowa State University Extension says the most common base material is quarried gravel, 3/4 inch and smaller, and that for vehicle traffic the portion passing a No. 200 sieve should be kept between 5% and 11%. That is why driveway bases are specified more tightly than patio bases. If you plan to park on pavers, see our page on driveway paver thickness.

When open-graded base needs extra protection

Open-graded stone lets water through, so clay or silt in the soil can migrate up into it over time. Belgard’s technical note recommends a highly permeable geotextile along the bottom and sides to act as a filter, and underdrains where the subgrade is fine-grained or water sources feed the area. Clay is common in parts of Arkansas, so this detail matters here. If you are curious about letting rain pass through the entire surface, read about a permeable paver patio.

Bedding sand and joint sand

Bedding sand is not the base. The sand layer, typically 1 inch of coarse bedding sand, is for final leveling, not drainage or structure. It is screeded smooth, and the pavers are set into it.

Specifications from the paving industry call for sand that is clean, non-plastic and free of foreign matter, made from natural or crushed rock, and they say plainly not to use stone dust. Concrete sand or masonry sand is not the same thing as bedding sand, so ask the supplier for a product that meets the paver bedding grading.

Two habits cause trouble:

• Filling low spots with sand. Iowa State Extension warns that sand deeper than 1 1/2 inches can create a washboard surface. Fix a low base with base stone, not sand.
• Compacting the sand before laying. The same source says not to compact the bedding sand. The pavers are compacted into it afterward.

Some open-graded systems use small stone for the setting bed instead of sand. Polycor’s installation guide specifies a 2 inch setting bed of ASTM No. 8 or No. 9 clean, washed stone in that case, kept at the thickness it was screeded.

Other base options and when they fit

Manufactured base panels

Plastic grid products exist. One manufacturer-side comparison notes that Gator Base, a polypropylene product, is recommended only for pedestrian areas and is not suitable for driveways. We pick compacted stone for permanent installs because it is proven across traffic types and handles Arkansas weather and soil movement well.

Recycled concrete aggregate

Crushed concrete is a common regional base. It compacts well and is often priced as a utility material. The same dense-graded rules apply: well-graded, crushed, compacted in lifts.

Concrete slab

A slab can serve as a base for heavy vehicle use or when a rigid, impermeable surface is needed, with a compacted aggregate subbase and proper reinforcement. Laying pavers over an existing slab is possible when it is sound. Nicolock advises replacing the slab when you see extensive structural cracking, significant settlement, areas that rock or move, drainage problems that cannot be corrected, or crumbling edges. If your slab shows those signs, have a hardscape contractor evaluate it before anything is laid on top.

Gravel patios

A loose gravel patio is a different build with different upkeep, but the base discipline is the same. See getting the base right for a gravel patio.

How thick should the base be?

There is no single number, and published guidance varies by source because climate and soil vary. Here is how the main sources line up.

The CMHA figures are minimums under ideal conditions. A published ICPI-aligned tech spec adds that in colder climates, continually wet or weak soils call for bases at least 2 to 4 inches thicker. Polycor says weak soils, wet climates, freeze-thaw and heavy loads may require greater thickness.

In our experience in Central Arkansas, the thing that pushes depth up is rarely traffic on a patio. It is soft, wet or clay-heavy subgrade, plus water running toward the area from a roof or slope. When we dig and find that, we plan for more base, better drainage and often geotextile.

Extend the base past the pavers

Polycor states that a dense-graded base should extend a minimum of 6 inches beyond the paved area, or a distance equal to the base thickness, whichever is greater. That support at the edges keeps the perimeter pavers from sagging.

Compaction and slope matter as much as the material

The best stone will still fail if it is dumped and raked. Compaction and grade decide the result.

• Lifts. Polycor’s guide calls for moistened material spread and compacted in 4 inch lifts, not one thick pass.
• Density. CMHA’s guide specification calls for compaction to not less than 98% Proctor density for pedestrian areas and residential driveways, and 98% modified Proctor for vehicular areas.
• Flatness. One regional guide lists final base surface elevations varying no more than 3/8 inch over a 10 foot straightedge.
• Slope. Iowa State Extension says the paved area should slope away from the house, with an example of a drop of 2 inches for every 8 feet. Belgard’s pro tips give a pitch of 1/8 to 1/4 inch per foot for patios. Our page on patio drainage design goes through slope in detail.

Set the slope in the base, not in the sand. That is the single easiest way to avoid ponding at the foundation.

Common mistakes in paver base work

1. Using rounded gravel or stone dust where crushed, graded stone belongs.
2. Skimping on depth over soft or wet soil.
3. Compacting one thick layer instead of thin lifts.
4. Using sand to level a base that is off.
5. Forgetting to slope water away from the house.
6. Leaving no base beyond the edge of the pavers, or no edge restraint.
7. Skipping geotextile or underdrains where clay or standing water is present.

After the install, keep the surface in shape. When it is time to seal, cleaning pavers before sealing properly gives the sealer a clean surface to bond to.

Our perspective

We have completed more than 2,000 projects across Central Arkansas, and what we tell every homeowner is the same: the base is where a patio is won.

A paver surface looks the same on day one whether the base is right or wrong. The difference shows up after a few wet seasons, when a poorly built patio starts to dip, rock or hold water. So we put our attention below the surface: excavating to the depth the soil calls for, choosing a compacted aggregate base that suits the drainage conditions, building in a slope away from the house and compacting in lifts.

That approach is why our hardscape work pairs quality materials with skilled craftsmanship. A good base is not exciting to look at, but it is what lets a patio shrug off heavy use and years of weather, with easy long-term upkeep. If something is wrong with your yard’s drainage or the ground is uneven, we deal with that first, because every paver on top depends on it.

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Plan your paver project with us

If you would rather have the base done right the first time, our crews handle excavation, base, bedding, paver installation and drainage for patios, walkways and more across Central Arkansas. Learn about our Decks and Patios work or our hardscape and stone masonry services, then reach out through our site to talk about your yard.

For design ideas before you call, browse our paver patio ideas and the most durable hardscape materials for Arkansas patios.

FAQ

What type of gravel should go under patio pavers?

Use crushed, angular stone, not rounded gravel. For a dense-graded base, that is a blend from 3/4 inch down to fine particles. For an open-graded base, it is clean, washed 3/4 inch stone, often called ASTM No. 57. Your site’s drainage should decide which you use.

Can I use sand alone under pavers?

Sand is only the thin bedding layer, about 1 inch, and is not a base. Without a compacted stone base under it, the surface settles and goes uneven. Iowa State Extension specifically cautions against using sand to make up for an inadequate base.

Can you use concrete as a base for pavers?

Yes, in some cases. A structurally sound slab with no active movement and good drainage away from the house can work. Heavy cracking, settlement or ponding water are signs it should be replaced, so have a contractor look at it first.

How far should the base extend past the pavers?

For a dense-graded base, Polycor says at least 6 inches past the paved edge, or a distance equal to the base thickness, whichever is greater. This supports the edge pavers and the restraint holding them.

Sources

• Base Installation, Polycor
• Pavers installation guide, Polycor
• Proper Concrete Paver Base and Depth, CMHA
• Guide Specification for the Construction of Interlocking Concrete Pavement, CMHA
• How To Install a Paver Patio Base, Unilock
• Paver Installation Basic Tech Guide, Unilock
• Installing Concrete Pavers, Part Two, Iowa State University Extension
• Construction of Interlocking Concrete Pavements tech spec
• Concrete Pavers Guide Specification, Tech Spec 9
• Installing the Best Paver Base, Belgard
• Using Open-Graded Aggregate with Standard Concrete Pavers, Belgard technical note
• Comparing Paver Base Materials, Western Interlock
• Base Material for Pavers, Floor Chem Depot
• Pavers Over Concrete, Nicolock
• Best Practices for the Installation, Care, and Maintenance of Pavers

Recommended

• Paver Base Depth 4 to 6 in, Exact Specs and 1.25× Ordering Math
• Patio Edging Options: Materials and How to Choose
• Dry Laid Patio: How It’s Built and When It Works
• Gravel Patio Pros and Cons: Homeowners, Get the Base Right