Artificial Turf Base Material: What to Use and How Deep
O'Leary Development GroupNovember 2, 2026
Choose the right base for artificial grass: Class 2 road base, crushed limestone or decomposed granite, how deep to lay it, how to compact it, and what to skip.
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The best base for artificial grass is a compacted layer of crushed, angular stone with some fines mixed in: Class 2 road base, crushed limestone, crusher fines or decomposed granite. Lay it 3 to 4 inches deep for a typical yard, compact it in repeated passes until it is firm, and grade it so water leaves the surface. Skip rounded pea gravel and loose sand as the main base. Everything below explains why, and how to match the material to your soil and your use.
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Use angular crushed stone with fines (Class 2 road base, crushed limestone, crusher fines or decomposed granite). Rounded stone shifts and will not lock together.
Plan on roughly 3 to 4 inches of compacted base for a typical residential lawn, and 4 to 5 inches for heavy traffic or pets. Wet or high-water-table sites can need up to 6 inches.
Compact to about 95%, lightly wetting the base as you go. Test by walking on it: if you leave footprints, keep compacting.
Sand is a leveling or finishing layer of no more than about 2 inches, never the structural base.
Know your native soil first. Clay holds water and needs more care than sandy or rocky ground.
The base is the part of an artificial lawn you never see, and it decides how the lawn looks in year five. It does two jobs. It is the firm surface the turf rests on, and it is the drainage layer. One manufacturer’s professional installation manual describes the base as both the drainage layer and the solid walking surface, and reports drainage of up to 12 inches of water per hour in most cases.
Get the base wrong and the symptoms are predictable: low spots where the ground settles, ripples or seams that show, puddles that linger, and weeds or odors where water sits. Turf itself has drainage holes, but it only drains as well as the stone underneath it.
Base materials compared
Several names describe nearly the same product. The installation manual above lists crushed stone, breeze rock, chat, decomposed granite, crusher fines, Class 2 aggregate and Class 2 road base as common names for the base layer. In San Antonio, you will most often hear “road base,” “flex base” or “crushed limestone.” Ask the supplier for the gradation instead of relying on the name.
Material
Good as the main base?
Notes
Class 2 road base
Yes
Mix of crushed stone and fines that compacts into a firm, stable layer. A common choice for residential lawns.
Crushed limestone
Yes
Angular, locally common in Texas, packs tightly. Choose a clean grade without excess dust.
Decomposed granite
Yes
Compacts well and is widely used under turf. Needs good drainage design beneath it.
Crusher fines / screenings
Top layer
Useful for smoothing and correcting small depressions on top of a coarser base.
3/4-inch to 1/4-inch crushed drain rock
Yes
Open, fast-draining. Often finished with a thin fines layer.
Pea gravel
No
Rounded, smooth stones shift and are hard to compact.
Sand
Only as a thin leveling layer
Not a structural base.
Fill dirt or topsoil
No
Fine for raising grade below the base, not for the base itself.
Class 2 road base
Decomposed granite and Class II road base are the two most common base materials, and the guidance across installation manuals is consistent: the base should be durable and drain well. Another manufacturer’s landscape installation manual recommends 3/8-inch crushed stone, also called Class 2 road base, decomposed granite or chat, spread evenly and graded to meet design and drainage requirements.
A third installation guide specifies a maximum particle size of 3/4 inch for DOT Class 2 aggregate or equivalent, and allows a mixed coarse-and-fine material such as crush-and-run. If your supplier offers #2 road base, that is the product to ask about for most residential turf bases.
Crushed limestone
Crushed limestone is a natural fit in South Texas. Its angular faces interlock when compacted, and its fines bind the layer so it stays firm. You can see the range we deliver on our crushed limestone aggregate page. The thing to watch is dust: a very powdery load with too many fines drains slowly.
Why fines matter, in both directions
The Sports Turf Managers Association notes that hardness, particle shape, size and gradation all affect how a base builds and performs. It wants aggregate that gives stability and free drainage while avoiding silts and excessive fines that block water flow. A sports-field specification goes further and caps material passing the #200 sieve at 5%. You do not need a lab test for a backyard, but the principle holds: some fines to bind, not so many that the base turns into a dust cake.
What not to use
Skip pea gravel as the base. A manufacturer’s installation guide says rounded, smooth stones shift and are difficult to compact. Pea gravel has a place in drainage trenches and play areas with the right design, but under turf it will feel soft and move.
Can you use sand as a base?
Not as the structural layer. One company guide says sand is better as a screed or finishing layer than as the base itself. The installation guide quoted above allows a thin fines layer, such as manufactured sand, to fill low spots or create a level surface, preferably no more than 2 inches, and compacted.
So the working answer: build on road base or crushed limestone, then use a thin layer of sand or screenings to dress the surface. If you need to order either, see our sand delivery and aggregate options.
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There is a range, and the right number depends on climate, drainage and use.
Standard outdoor base: the installation manual cited earlier recommends 4 inches, as little as 2 inches in arid climates, and up to 6 inches where rainfall or water tables are high.
Typical residential lawn: the Turf Network points to 3 to 4 inches of compacted base as a best-practice starting point, depending on the application and property.
Heavy traffic or pets: one turf company recommends 4 to 5 inches, and 4 to 6 inches for playgrounds, plus a shock pad where fall-safety ratings are required.
Sports areas or cart paths: the same guide says 6 to 8 inches may be appropriate after confirming loads and subgrade.
For a San Antonio backyard with average use, 3 to 4 inches is the working number. Go toward 4 to 6 inches if your yard collects water, if the soil under it is soft or organic, or if you expect heavy traffic.
Estimating how much to order
Bulk aggregate is sold by the ton or cubic yard. Multiply length by width in feet by the depth in feet to get cubic feet, then divide by 27 for cubic yards. A 20 by 30 foot lawn (600 square feet) at 4 inches deep is 600 x 0.333 = 200 cubic feet, or about 7.4 cubic yards. Compacted stone settles, so order a little extra, and confirm the conversion to tons with your supplier. Our guide on how much fill dirt you need uses the same math for volume.
Soil and drainage: match the base to your ground
The base sits on your native soil, and the soil changes the plan. The Sports Turf Managers Association guidelines say base selection depends on use, climate, rainfall and site conditions, and that native soils vary substantially even within one region. Sandy soils may absorb significant rainfall, while clay may fill like a bathtub.
In practice around Bexar County, that means walking the yard before you order anything:
Dig a test hole 12 inches deep, fill it with water, and see how long it takes to drain. Standing water after several hours is a warning.
Note where water goes during a heavy rain. Turf needs a slight slope away from buildings. The manufacturer guide recommends sloping toward a drainage area to prevent pooling, even though the turf itself drains through its holes.
Treat clay seriously. One turf company says clay or expansive soils, heavy rain, poor drainage and soft or organic subgrades justify additional base depth or preparation.
If the yard is low or uneven, build it up first with clean fill, then add the base on top. Our select fill is a sandy clay mix used for building pads, and a guide to where to buy fill dirt covers how to pick a source. Fill goes below the base. It never replaces it.
Weed barrier and geotextile fabric
A non-woven geotextile over the compacted base is a common detail. A professional specification calls for a non-woven geotextile membrane over the compacted sub-base, connected subsurface drainage, and at least 4 inches of porous, free-draining stone. The same document allows a porous non-woven polypropylene stabilization fabric, depending on geographic location.
Keep two points in mind. Use a permeable fabric, never plastic sheeting, which blocks drainage. And remember a fabric reduces weeds but a clean, compacted base with no organic matter does most of the work. Strip old sod and roots before you start.
Step by step: building the base
Excavate to the total depth of base plus a little for the turf and any sand layer. Remove sod, roots and organic soil.
Remove the waste. Old sod, concrete and soil add up fast. We haul away loads under our dump truck haul-off service, listed at $275 per truck load.
Compact the subgrade with a plate compactor so the base does not sink into soft ground.
Wet lightly and compact. The installation manual recommends compacting to about 95%, rejecting anything under 85%, wetting without saturating, and repeating passes until the surface is smooth and stable.
Fix low spots with screenings or stone dust, then check level and slope. That manual calls for a 1% grade; a sports specification allows 1/4 inch of variation in 10 feet on the finished aggregate.
Footprint test. The installation guide suggests that if you leave footprints, the base is still under-compacted. Required compaction targets differ by manufacturer (one landscape manual says at least 90%), so follow the one for your turf.
Our driveway base preparation article applies the same 95% compaction and lift logic to a larger surface, and it is a useful reference for the equipment you will need.
Getting the material to your yard
Base material is heavy. A lawn of 600 square feet at 4 inches needs several tons, which is far more than a pickup bed should carry. Most homeowners have it delivered by dump truck and dumped on a tarp or in the driveway close to the work area. If you plan to haul smaller amounts yourself, read up on trailer sizing and safe hauling before loading a trailer with dense aggregate.
When you arrange delivery, tell the dispatcher the width of the access gate or driveway, where the truck can drop, and whether the ground is soft. Dump trucks are heavy and can leave ruts in wet lawns.
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Promo: base material delivered in Greater San Antonio
We deliver road base, crushed limestone, sand, fill dirt and topsoil across Greater San Antonio, with same-day and next-day dispatch, per-load pricing and GPS-tracked trucks. Contractors and homeowners can request a quote online, and we can also haul off the old sod and soil you dig out.
Most turf failures we hear about trace back to the ground, not the grass. Homeowners spend on the turf and treat the base as an afterthought, then wonder why the lawn ripples or holds water.
Our view is simple. Choose angular crushed stone with fines, such as road base or crushed limestone, order enough to lay it at the right depth, and compact it properly. A few extra hours with a plate compactor cost far less than lifting a finished lawn to fix it.
We supply locally sourced aggregate and deliver it in San Antonio and surrounding cities, so you can match the material to your project instead of settling for what fits in a truck bed. When you are not sure of the grade or quantity, call us before you order. We would rather size the load correctly the first time.
BRIAN
Common mistakes to avoid
Using pea gravel because it looks clean. It shifts. Use crushed angular stone.
Skipping compaction in thick layers. Spread and compact in lifts rather than one deep pass.
Ignoring slope. A flat base on clay can hold water even though the turf has holes.
Laying plastic under turf. Use a permeable fabric if you want a barrier.
Leaving organic matter. Roots and sod decompose and settle.
Over-relying on sand. Keep it to a thin leveling layer.
FAQ
What is the best base for artificial grass?
A compacted layer of angular crushed stone with fines, such as Class 2 road base, crushed limestone or decomposed granite. These materials lock together, stay firm underfoot and drain well. Most residential lawns use 3 to 4 inches.
Can I put artificial grass directly on dirt?
It is not recommended. Dirt compresses unevenly, holds water and grows weeds, so the turf will settle and ripple. A compacted aggregate base gives you a stable, draining surface that supports the lawn for years.
Is pea gravel or sand okay under turf?
Not as the main base. Pea gravel is rounded and shifts, and sand does not give the structure turf needs. A thin layer of sand or screenings on top of road base is fine for leveling.
How much base do I need for a 500 square foot lawn?
At 4 inches deep, you need about 6.2 cubic yards before settling (500 x 0.333 / 27). Order a little extra and ask your supplier to convert the volume to tons for the specific material.
