Paver Quantity, Base & Sand
Paver counts, base aggregate, bedding and joint sand — and why the sand is a bedding layer rather than a levelling one.
The build-up, top to bottom
Sand beds, it doesn't level
The bedding sand is a bedding layer, not a levelling layer. It goes down as a uniform inch, screeded, and all the levelling happens in the base underneath. Using sand to fill a low spot feels like the obvious shortcut and it guarantees that spot will sink — sand compresses in proportion to its depth, so an inch beside three inches settles differentially by about 0.2″. That's a visible dip, and no amount of re-sanding afterwards fixes it. If the base isn't flat, fix the base.
And you have to order more base than you need. Crushed aggregate loses about a fifth of its volume going from loose-dumped to properly compacted, so 4″ of compacted base needs 5″ of loose stone — 25% more than the finished depth suggests, at every depth. Ordering to the compacted figure is the standard way to end up a third of a load short with the excavation already open.
Compact in lifts. A plate compactor reaches three to four inches down and no further, so an 8″ base dumped in one go and run over once has a compacted top and a loose bottom. It settles later and takes the surface with it, months after anyone would connect the two.
- Edge restraint is structural, not trim. Pavers spread sideways under load — that's what the interlock resists — and without something holding the perimeter, the field creeps, joints open and the sand washes out.
- Herringbone needs a paver exactly twice as long as it is wide. A 6 × 9 won't run one, however much you want it to.
- Herringbone is the driveway pattern because no joint runs in the direction of travel. A car braking on running bond drives the courses apart.
- Sweep the joint sand twice — before and after compacting. The first pass only half fills the joints, and joints that aren't full don't interlock.
- Set the fall in the base, not the screed. About ¼″ per foot away from buildings. Building fall into the sand is the levelling-layer mistake in a different disguise.
How to use
- Enter the area and what the surface has to carry.
- Order the LOOSE base figure, which is 25% more than the compacted depth.
- Screed the bedding sand to a uniform inch and level in the base instead.
- Budget for edge restraint — it is structural, not trim.
Frequently asked questions
How thick should the bedding sand be?
One inch, uniform, screeded — and that is a specification rather than a guideline. The bedding sand is a bedding layer, not a levelling layer, and every bit of the levelling belongs in the base underneath it. A thicker bed is not a safer bed; it is a bed that will settle more.
Can I use sand to level out a low spot?
You can, and that spot will sink. Sand compresses in proportion to its depth, so an inch beside three inches settles differentially by about two tenths of an inch under compaction and traffic. That is a visible dip in a paved surface, it appears within the first season, and no amount of re-sanding the joints afterwards fixes it. If the base is not flat, fix the base.
How much base do I need under pavers?
Four inches compacted for a patio or walkway on soil that drains, six on clay or where it freezes, eight for a residential driveway, and twelve for a driveway over clay in a cold climate. The base is the part nobody sees and the part that decides whether the job lasts — when in doubt, more base.
Why do I need to order extra base?
Because crushed aggregate loses roughly a fifth of its volume going from loose-dumped to properly compacted. Four inches of compacted base needs about five inches of loose stone, which is twenty-five per cent more than the finished depth suggests, and the same proportion applies at every depth. Ordering to the compacted figure is the standard way to end up short with the excavation already open.
Why compact the base in lifts?
Because a plate compactor only reaches three to four inches down. An eight inch base dumped in one go and run over once has a compacted top and a loose bottom, which settles months later and takes the surface with it — long after anybody would connect the two events. Two lifts of four inches take slightly longer and are the whole difference.
How many pavers per square foot?
Four and a half for a standard 4 by 8 Holland stone, four for a 6 by 6, and one for a 12 by 12 slab. It comes straight from the face area, so any paver can be worked out by dividing 144 by its length times its width in inches. Add five per cent for cutting on a simple pattern and up to fifteen on a 45 degree herringbone.
Which pattern should I use for a driveway?
Herringbone, at 45 degrees if you can. It interlocks in both directions and no joint runs in the direction of travel, which matters because a car braking on a running bond drives the courses apart. It generates the most cutting of any pattern and it is worth it — the pattern is doing structural work on a driveway in a way it is not on a patio.
Why will herringbone not work with my pavers?
Because it needs a unit exactly twice as long as it is wide. A 4 by 8 runs a herringbone perfectly; a 6 by 9 is a two-to-three ratio and cannot, however much you want it to. Forcing it means cutting every single unit, which destroys the interlock that is the entire reason for choosing the pattern.
Do I really need edge restraint?
Yes — it is structural rather than decorative. Pavers spread sideways under load, which is exactly what the interlock is resisting, and without something holding the perimeter the field creeps outward, the joints open and the jointing sand washes out of them. It is the commonest reason a paver surface looks tired after three years, and it is among the cheapest parts of the job.
What does the joint sand do?
It transfers load between units, which is what makes a paver surface behave as a pavement rather than as a lot of separate stones. Sweep it in, compact, and sweep again — the first pass only half fills the joints, and joints that are not full do not interlock. Polymeric sand resists washout better and is worth it on anything sloped or exposed.
What fall should a paved surface have?
Around a quarter of an inch per foot, away from buildings. Set it in the base and carry it through the screed rather than building it into the sand — varying the sand depth to create fall is the levelling-layer mistake wearing a different hat, and it settles unevenly for exactly the same reason.
How much digging is this?
More than people expect, and usually more than the material going back in. The excavation is the base depth plus an inch of sand plus the paver itself, so a driveway over clay means digging around fifteen inches below finished level. It is worth working out the spoil volume before starting, because moving it is frequently the largest single job on the list.
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