Which Sand Goes Under Pavers?
Pavers sit on a bed of washed concrete sand meeting ASTM C33, screeded about 1 inch deep and left uncompacted, over a packed crushed-stone base. A different, finer sand goes in the joints between pavers after they're laid. Mixing the two up, or substituting mason sand or stone dust for the bedding layer, is one of the most common paver mistakes.
Key Takeaways
- Bedding sand (under the pavers) is washed concrete sand, ASTM C33 or equivalent, screeded to an uncompacted nominal 1-inch layer (ICPI Tech Spec 2).
- Joint sand (between pavers, after they're set) can be a finer sand meeting ASTM C144, or a polymeric sand for added stability.
- Masonry sand, limestone screenings, and stone dust should never be used as bedding sand; they don't compact uniformly and can trap moisture under the pavers (ICPI Tech Spec 2).
- The compacted base beneath the sand should run at least 4 inches for walkways and patios, and at least 6 inches for driveways, on well-drained soil (ICPI Tech Spec 2).
The Layers, Bottom to Top
A paver patio or walkway is built in distinct layers, and each one does a different job. Getting the order and the materials right is what keeps pavers from shifting, rutting, or holding water.
1. Compacted base
The foundation layer is a dense, crushed aggregate, compacted in lifts rather than dumped and packed once. Industry guidance calls for a minimum 4-inch compacted base under pedestrian areas like walkways and patios on well-drained soil, and a minimum 6-inch base under residential driveways; continually wet or weak soils need 2 to 4 inches more on top of either figure (ICPI Tech Spec 2, 2020). WAYS's #57 crushed limestone is a common pick for this layer, compacted in roughly 2-inch lifts with a plate compactor.
2. Bedding sand
On top of the compacted base goes a layer of washed concrete sand, the same material covered by ASTM C33 (or CSA A23.1 in Canada). It's screeded flat to a nominal, uncompacted 1-inch thickness right before the pavers go down (ICPI Tech Spec 2, 2020). This layer is never compacted on its own; it's meant to settle and lock the pavers in place once they're placed and vibrated down together. Concrete Sand is the product for this step.
Masonry sand (sold for mortar), limestone screenings, and stone dust should never be used here. They don't have the uniform, sharp-grained particle shape concrete sand has, so they can compact unevenly or block drainage through the bedding layer (ICPI Tech Spec 2, 2020).
3. Pavers, then joint sand
Once the pavers are placed on the screeded bedding sand, a vibratory plate compactor seats them into the bed and forces sand up into the joints between units. Dry joint sand, which can be a finer sand meeting ASTM C144 or a polymeric sand designed to stabilize the joints, is then swept across the surface and the pavers are compacted again until every joint is full (ICPI Tech Spec 2, 2020).
From the ground up: a compacted crushed-stone base (4 in for patios, 6 in for driveways), then an uncompacted 1-inch layer of ASTM C33 concrete sand, then the pavers, then a finer sand or polymeric sand swept into the joints.
Why Not Just Use One Sand for Everything?
Bedding sand and joint sand do different jobs, and a sand that's good at one is often bad at the other. Bedding sand needs to screed flat and stay put without compacting hard, so the pavers can settle evenly into it. Joint sand needs to pack tightly into a narrow gap and resist washing out, which is why a finer sand, or a polymeric sand that hardens slightly when wetted, works better there.
Using one all-purpose sand for both steps is the shortcut that shows up later as uneven pavers, joints that wash out in heavy rain, or a bed that holds water instead of draining through it. The extra step of buying two sand products is small compared to redoing a patio.
Frequently Asked Questions
What kind of sand goes under pavers?
Washed concrete sand meeting ASTM C33 (or CSA A23.1) goes under pavers, screeded to an uncompacted layer about 1 inch deep over a compacted crushed-stone base. It's often just called "concrete sand" at a materials yard.
Can I use regular sand or play sand under pavers?
No. Play sand and most general-purpose sands aren't graded the way concrete sand is, so they don't screed or settle consistently under the weight of pavers and foot or vehicle traffic. Stick to concrete sand (ASTM C33) for the bedding layer.
What's the difference between bedding sand and polymeric sand?
Bedding sand sits under the pavers, in a 1-inch uncompacted layer, and its job is to let the pavers settle flat. Polymeric sand goes in the joints between pavers after they're laid, and it's formulated to firm up when it gets wet, which helps keep joints from washing out or growing weeds.
How deep should the base be under pavers?
At least 4 inches of compacted crushed stone for walkways and patios on well-drained soil, and at least 6 inches for driveways. Wet or poorly drained soil needs 2 to 4 inches more on top of those minimums.
Can I skip the sand and set pavers directly on the base?
No. Without the bedding sand layer, pavers sit directly on an uneven, rigid base and have no way to settle flat under load. The sand layer is what lets each paver find its own level, which is the whole point of an interlocking (not mortared) paver system.
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