Choosing the right bedding sand for a paver patio

When you picture a new paver patio, you probably think about color, pattern and where the chairs will go. The thin layer underneath deserves some attention, too. Bedding sand helps seat the pavers evenly and supports the way the finished surface works together.

For homeowners in Southwest Washington, the useful questions are straightforward: Which sand belongs under the pavers, how deep should it be, and where will the water go?

Start with the paving system

This advice applies to conventional sand-set concrete pavers over a compacted aggregate base. Permeable pavers use a different assembly, typically with small, open-graded crushed stone in the bedding layer and joints. Porcelain slabs and other paving products may also have different requirements. Follow the instructions for the actual system you are installing rather than mixing methods.

Choose washed concrete sand

For a conventional sand-set installation, look for clean, washed concrete sand meeting the specified ASTM C33 grading requirements. That name describes a controlled range of particle sizes, not just sand that looks coarse. The Concrete Masonry & Hardscapes Association also calls for limits on very fine material.

Masonry sand, stone dust and limestone screenings are not substitutes for the specified bedding sand. Too many fine particles can interfere with drainage, and unsuitable material can break down or settle unevenly. Ask for the supplier's grading information and compare it with the paver manufacturer's requirements.

Keep the layer thin and even

The usual starting point is a nominal 1-inch layer of loose, screeded sand. That one-inch target applies before the pavers are compacted into place. Aim for a consistent thickness across the prepared base.

Screed rails help make that layer consistent. Set rails of the appropriate actual height on the prepared base, pull a straight screed board across them, then lift out the rails and fill the grooves. Leave the surface undisturbed until the pavers are placed. For this conventional method, do not compact the bedding sand first.

If the base has a low spot, correct the base. Adding extra sand to hide it creates a thicker pocket that can settle differently from the rest of the patio.

Bedding sand and joint sand have different jobs

Bedding sand goes below the pavers. Jointing material fills the spaces between them and helps the units work together. Some bedding sand moves upward into the joints during initial compaction, but that does not finish the joint-filling step.

Choose joint sand or a polymeric jointing product that suits the pavers, joint width and installation method. Polymeric sand has its own placement and watering directions; it is not a replacement for the bedding layer.

Plan for water, not just a level-looking surface

Before the sand goes down, the base needs the correct grade, compaction and drainage details. A patio or walkway should carry surface water toward the intended outlet, not toward the house. The assembly also needs to keep bedding sand from escaping into gaps or migrating into the base.

White deposits on concrete pavers, called efflorescence, are a separate issue. Moisture can carry dissolved compounds to the surface, where deposits remain or form as the water dries. Sand texture alone does not explain it. Correct materials and water management matter, but coarse sand cannot guarantee an efflorescence-free patio.

Before you order

Have the paving-system instructions, measured area and specified bedding depth handy. Our coarse sand page describes the clean, washed material we stock for paver screeding and includes a yardage calculator. Confirm the current grading specification and quantity for your installation before ordering.

For planning, a 12-by-12-foot area at one inch deep contains about 0.44 cubic yard of sand before any allowance for handling loss. Keep bedding, base aggregate and jointing quantities separate. A little care with these details gives the visible part of the project a much better start.