Almost every failed paver patio fails for the same reason: a bad base. The pavers themselves rarely wear out — they sink, tilt, and pop loose because the layers underneath were too thin, the wrong material, or never compacted. Get the base right and a paver surface stays flat for decades. This guide explains the two-layer base every project needs, exactly how deep each layer should be, and which sand and gravel actually belong under your pavers.
The Two-Layer System Every Paver Project Needs
A proper paver base is not one material — it's two distinct layers, each doing a completely different job. Skipping or combining them is the root of most paver problems.
The bottom layer is a compacted gravel base, 4 to 6 inches deep. This is the structural foundation. Crushed gravel, compacted in stages, spreads the load from foot traffic or vehicles across the soil and gives water a path to drain instead of pooling. Without it, pavers ride directly on native soil that swells when wet, heaves when it freezes, and settles unevenly under weight.
On top of the gravel sits a 1-inch sand bedding layer. This thin, screeded layer of coarse sand is purely for leveling — it lets you seat each paver to an exact height and locks the units in place once compacted. One inch is the standard: thicker sand beds rut and wash out, creating the very dips you're trying to avoid.
Both layers are mandatory. Gravel without sand leaves you no way to fine-level the pavers; sand without gravel gives the surface no structure and no drainage. Together they form a base that drains, carries load, and holds its shape — which is exactly why a quality paver installation always has both.
How Deep Should Each Layer Be?
Depth is driven by the load the surface carries. A garden walkway needs far less base than a driveway that parks a truck. The sand layer stays at 1 inch across the board; it's the gravel base that grows with the load.
| Project Type | Gravel Base Depth | Sand Layer | Total Base Depth |
|---|---|---|---|
| Walkway / path | 4″ | 1″ | 5″ |
| Patio | 4–6″ | 1″ | 5–7″ |
| Driveway (light vehicles) | 8″ | 1″ | 9″ |
| Driveway (heavy vehicles) | 10–12″ | 1″ | 11–13″ |
| Pool deck | 6″ | 1″ | 7″ |
In cold climates with deep frost, add a couple of inches to the gravel base — more compacted stone means more drainage and less frost heave. When in doubt, go deeper on the gravel; it's cheap insurance against a surface that telegraphs every wet season.
Gravel Types for Paver Base
Not all gravel is base gravel. The single most important property is that the stone is angular and graded — meaning it contains a mix of sizes from roughly 3/4 inch down to fine "fines."
Crushed stone (often sold as "crushed gravel," "road base," "Class 5," or "3/4-inch minus") is the correct choice. Its jagged faces lock together under a plate compactor, and the fines fill the gaps to create a dense, nearly solid layer that won't shift. This interlock is what carries load without rutting.
Recycled concrete aggregate is crushed, screened old concrete. It's angular, compacts much like crushed stone, drains well, and is usually cheaper and greener. It's an excellent base material where it's available and clean.
Pea gravel is wrong for paver base. Its stones are small, smooth, and uniformly round, so they roll past each other instead of locking. Pea gravel will not compact into a stable layer — pavers set on it shift and settle almost immediately. Save pea gravel for decorative paths and drainage fill, never for the structural base under pavers.
Sand Types for Leveling
Sand causes more confusion than any other base material, because two completely different products both get called "paver sand."
Coarse bedding sand — also sold as concrete sand or sharp sand — is what goesunder the pavers as the 1-inch leveling layer. Its angular grains lock together and hold a screeded grade so pavers sit level and stay put. This is the only sand that belongs beneath your pavers.
Polymeric sand is a fine sand mixed with binders that harden when wetted. It goes between the joints after the pavers are laid, not under them. Swept into the gaps and misted with water, it sets up to lock pavers together, resist weeds, and keep ants and washout at bay. Using polymeric sand as a bedding layer is a classic mistake — it hardens into a rigid, non-draining slab that cracks and traps water. Bedding sand goes under; polymeric sand goes in the joints on top.
How to Calculate Base Materials
Both layers are volume calculations: area × depth, converted to cubic yards. Let's work a 200 sq ft patio with a 4-inch gravel base and a 1-inch sand layer.
- Gravel base: 200 sq ft × (4 ÷ 12 ft) = 66.7 cubic feet. Divide by 27 to get cubic yards: 66.7 ÷ 27 ≈ 2.5 cubic yards. Because gravel compacts, order another 15–20% so you finish at the full 4 inches after tamping — call it about 3 cubic yards.
- Sand layer: 200 sq ft × (1 ÷ 12 ft) = 16.7 cubic feet, or 16.7 ÷ 27 ≈ 0.6 cubic yards of coarse bedding sand.
That's the method for any size project. Rather than running it by hand, plug your dimensions into the Gravel Calculator and Sand Calculator for exact tonnage and bag counts, or let the Paver Calculator size the pavers, base gravel, and bedding sand together in one pass.
Mistakes That Cause Paver Failure
- No compaction. Dumping gravel and raking it smooth isn't a base. Compact in 2-inch lifts with a plate compactor, and tamp the bedding sand and the finished pavers too. Uncompacted base settles unevenly within the first season.
- Wrong sand type under pavers. Fine play sand or polymeric sand as a bedding layer won't hold a grade or drain. Use only coarse bedding sand beneath the pavers, and save polymeric sand for the joints on top.
- Skipping edge restraints. Without a solid edge — plastic paver edging, a concrete curb, or a soldier course — the outer pavers spread outward, joints open up, and the whole field loosens. Edge restraints hold everything tight.
- No slope for drainage. A paver surface needs a slight pitch — about 1/4 inch per foot — away from the house so water sheets off instead of sitting in the base. A perfectly flat patio ponds, and trapped water undermines everything below.
Bringing It Together
A lasting paver project is really a base project: 4 to 6 inches of compacted angular gravel, a screeded 1-inch coarse-sand bed, edge restraints, and a touch of slope. Size each layer with the Paver Calculator, the Gravel Calculator, and the Sand Calculator before you order. Building a raised patio or a seat wall around it? The Retaining Wall Block Calculator sizes the block courses and base for that, too. Get the layers right once and the pavers take care of themselves.