How to lay a paver patio: base, sand, edging and joints
Dig out the patio and 6 inches past it, compact a crushed stone base at least 4 inches deep in layers, set the edging on it, screed an inch of concrete sand, lay the pavers, then run a plate compactor over them and sweep sand into the joints.
The base does the work, so it decides how long the patio stays flat. Belgard asks for at least 4 inches of compacted base under a patio or walkway and 6 under a driveway, more where the ground freezes, and a slope of at least 2% so rain runs off. Call 811 before you dig.
Worked example
Example: a 16 × 12 ft patio of 4 × 8 in pavers on 4 inches of compacted base reaching 6 inches past the edges, with 1 inch of sand and 5% extra for cuts.
This example gives 908 pavers, 4 × 8 in.
- Patio: 16 × 12 = 192 sq ft
- 144 ÷ (8 × 4) = 4.5 pavers a square foot
- 192 × 4.5 × (1 + 5/100) = 907.2, rounded up to 908 pavers
- Base area: the paved area with the base 6 in past every edge = 221 sq ft
- Base: 221 sq ft × 4 in ÷ 12 ÷ 27 × (1 + 25/100) for compaction = 3.41 cu yd × 1.48 = 5.05 tons
- Sand: 192 sq ft × 1 in ÷ 12 ÷ 27 × (1 + 5/100) = 0.62 cu yd, or 34 bags of 0.5 cu ft
- Joint sand: 192 sq ft ÷ 65 sq ft a bag = 2.95, rounded up to 3 bags of 50 lb
Call 811 and plan the slope
Call 811 a few working days before you dig, so the utility lines are marked free of charge. Mark the patio out with stakes and string or marking paint. Plan its fall away from the house: Belgard asks for a slope of at least 2%, so a patio 12 ft deep drops about 3 inches from the house to its far edge.
Dig deeper and wider than the patio
Belgard’s guide digs at least 8 inches below the finished surface, 10 or 12 where the ground freezes, and at least 6 inches past the pavers on every side, or as far as the base is deep if that is more. Compact the soil at the bottom and give it the same slope. Over soft soil, a geotextile fabric laid on it and up the sides keeps the soil out of the base.
Build the base in layers
Use road base, the crushed stone with fines that Belgard asks for, which locks together when it is packed. Spread it 2 to 4 inches at a time, lightly damp, and compact each layer before the next, with extra passes along the edges and in the corners, where a patio settles first. Belgard’s construction guidelines ask for a reversible plate compactor of at least 7,000 lb of force on the base: say so when you rent one. Finish it flat, within 3/8 inch under a 10 ft straightedge, with no hollows for the sand to run into: the sand bed stays an even inch.
Set the edging
Belgard puts the edge restraint on the compacted base before the sand, wherever the pavers do not run against a wall or a curb. Alliance’s Gator Edge Rigid comes in 8 ft pieces that twist and lock together; its instructions call for one 10-inch nail in every second hole and at every joint. Cutting the bridges between its triangles lets it bend around a curve.
Screed an inch of concrete sand
Lay two pipes 1 inch across on the base, 6 to 8 ft apart, fill between them with concrete sand, moist but not wet, and pull a straight board across the pipes until the sand is smooth. Lift the pipes out, fill their grooves and smooth them with a trowel. Belgard says never to use masonry sand, screenings or stone dust, and not to walk on the screeded sand.
Lay the pavers
Start at a square corner, lay a border row along the edges, then fill in the pattern, with a string line to keep the rows straight and joints of about 1/8 inch. Screed more sand as you go. Cut the pieces along the edges with a diamond blade, and wear eye, hearing and breathing protection when you cut, as Belgard asks.
Compact, then fill the joints
Run a plate compactor of at least 5,000 lb of force over the pavers, with cardboard, thin carpet, thin plywood or a rubber mat under it so it does not mark them. Sweep dry joint sand over the surface and compact again, pass after pass, until the joints are full; top them up as the sand settles. Belgard recommends polymeric joint sand, which stays in the joints and helps lock the pavers in place and keep weeds and debris out: follow its maker’s instructions to the letter.
Look after it
Wind, water and traffic carry joint sand away, faster on a slope. Belgard says to refill the joints once the sand has dropped more than 1/2 inch below the bottom of the pavers’ beveled edge. Keep a few spare pavers: one can be lifted out and replaced.