What Goes Under Your Pavers, and How Much of It

Pavers that sink at one corner, rock underfoot or lift after a wet winter almost always have the same cause, and it is not the pavers. It is what is underneath them. A paved area is three layers, and only the top one is decorative.

The three layers

1. Pavers
2. Bedding layer — 25–30mm of sand or crusher dust, screeded level, not compacted
3. Compacted base — 100–150mm of crushed rock, compacted in layers

Plus geotextile fabric between the base and the subgrade on any clay site, which is most of Melbourne.

The base: crushed rock, always

This is the layer that carries the load. For a patio or a path, Crushed Rock Class 3 20mm is enough — use it for pathways, light-duty driveways and general fill.

If a car will ever park on it, use Crushed Rock Class 2 20mm, which is engineered for driveways and vehicle-rated sub-base, or 20mm Roadbase — used for driveways, shed bases, under-paving sub-base and trench backfill. On a budget, Recycled 20mm Roadbase does the same job from recycled concrete and masonry.

Compact in 50–75mm layers. Wet each layer lightly, plate-compact, then add the next.

The bedding layer: sand or crusher dust

This layer exists to let you level the pavers, not to support them. It is screeded flat and left loose — compacting it defeats the purpose.

Packing Sand is the usual choice: use it for bedding pavers, backfill and general landscaping, where its consistent texture spreads and screeds easily. 5mm Crusher Dust is the alternative and is used for paver bedding layers, pathway top dressing and joint filling — its fine, even grade compacts to a smooth firm finish, which some pavers prefer under natural stone.

Keep it to 25–30mm. A thick bedding layer is the single most common cause of pavers settling unevenly, because sand consolidates under load and a deep layer consolidates unevenly.

The joints

Washed Sand is the one to use here — use it for concreting, filling paver joints and general construction where a clean, screened product is needed. Brush it into the joints dry, compact the pavers, then brush more in. Full joints are what stop pavers rocking.

Quantities for a 20m² patio

Layer	Depth	Order
Crushed rock base	100mm compacted	~2.5m³
Bedding sand	30mm	~0.7m³
Joint sand	—	~0.2m³

The base figure includes roughly 20 percent extra for compaction. Round bedding and joint sand up rather than down — running out of screed sand halfway across a patio means stopping and waiting for another delivery.

Ordering sensibly

Base and bedding are different materials, so they arrive as two loads and are charged as two deliveries. If you can use the same sand for bedding and joints, do — it turns three loads into two. And if the whole job is under 8m³ of each material, each one is a single load.

Browse Crushed Rock, Sand and Aggregates, or read more on choosing a sand grade and choosing a crushed rock base.