Pavers fail from the bottom up. Sunken ruts, rocking pavers and weeds almost always trace back to too little base, poor compaction or bad drainage. Estimate the layers properly and the pavers take care of themselves. This guide works through a paved area from the dig to the joint sand.
The layers
- Excavation: the total depth of every layer plus the paver thickness, minus how high the finished surface will sit above the surrounding ground.
- Sub-grade: the natural ground, compacted. Dig out soft spots and replace them with base material.
- Geotextile on clay or soft soils, to stop the base sinking into the ground below.
- Base: road base (crushed rock), compacted in layers.
- Bedding: 20–30 mm of washed bedding sand, screeded flat and not compacted.
- Pavers and edge restraint.
- Joint sand: paving joint sand or polymeric sand, swept in and vibrated down.
How thick?
| Use | Road base |
|---|---|
| Paths and patios | 75–100 mm |
| Driveways (cars) | 150–200 mm |
| Poor or clay ground | Add 50–100 mm and geotextile |
Compact the base in layers no thicker than about 75 mm with a plate compactor. One thick layer compacted once will settle later, under the pavers.
Fall and drainage
Patios need a fall so water runs away from buildings: about 1:60 to 1:100. Build the fall into the base, not the sand bed; sand that varies in thickness settles unevenly. Keep the finished surface below the slab edge and clear of weep holes; the NCC generally wants at least 50 mm between a house slab and paving that falls away from it, and where a patio meets a door threshold, add a drainage channel.
Quantities
Pavers: area ÷ (paver + joint module), plus 5–10% waste. Allow 12–15% for herringbone, circles and lots of curves, where every edge piece is a cut.
Base: area × depth, plus about 20% for compaction. Road base is sold by the cubic metre or the tonne, at roughly 2 tonnes per compacted cubic metre.
Bedding sand: area × bed depth. One cubic metre of bedding sand covers about 33 m² at 30 mm.
Joint sand: depends on joint width and paver size. A 20 kg bag of paving joint sand covers roughly 5–8 m² of pavers with narrow joints.
Edging: the perimeter, less any edge already held by a wall or kerb.
The paver calculator works out every layer, the joint sand and the edging in one go.
A worked example
A 5 × 4 m patio (20 m²) in 200 × 100 mm pavers with 3 mm joints: about 48.5 pavers per m², so 970, plus 10% = 1,067. Road base at 100 mm plus 20% compaction: 2.4 m³, about 5 tonnes. Bedding sand at 30 mm: 0.6 m³. Four 20 kg bags of joint sand and 18 m of edge restraint.
Don't forget
- Removing the dug soil, which swells when dug and takes more skip bins than you'd think
- Plate compactor and block splitter or saw hire
- Drainage channels at thresholds
- Weed membrane where specified
- Sealer, if the client wants a wet look or stain resistance
Choosing pavers
Concrete and clay pavers are typically 40–50 mm thick for patios and paths, and 60–80 mm for driveways. Natural stone such as bluestone, sandstone and travertine is often laid on a mortar bed or over a concrete slab, which changes the takeoff. Check the manufacturer's laying guide, which gives the base depth and joint width for each product.
Laying patterns and waste
Stretcher bond (running bond) is the simplest pattern and wastes the least. Basketweave is similar. Herringbone at 45° looks great and locks well under traffic, so it's often used on driveways, but every edge piece is a cut. Circles and fans usually come as kits with their own counts. Price the extra labour for cut-heavy patterns as well as the extra material.
Labour notes
Excavation and base preparation usually take longer than laying. A crew that lays 20–30 m² of blocks in a day might spend two days digging, removing spoil and compacting the base for the same area. Price each stage separately so the client can see where the time goes.
Common questions
Can pavers go straight onto soil?
Not if you want them to stay flat. Without a compacted base they rut, rock and settle within a season or two.
Can I lay over an old concrete slab?
Sometimes, if the slab is sound, falls the right way and leaves room for the paver height below thresholds and damp courses. Water must drain off the slab and out through the edges, so plan drainage holes or channels.
This guide is general information for estimating. It is not engineering, legal or tax advice. Check the NCC, Australian Standards and your building surveyor or certifier for your project.