TradesHow this works
Enter the paved area and what it is for. The tool sets the base depth by the load, works out the compacted gravel base and the bedding sand, and adds the compaction allowance so the gravel you order matches what ends up in the ground. It shows all three use levels so you can see what the load costs in base.
The pavers are the easy part; the base is where patios and driveways fail. Build it deep enough for the load, compact it in lifts, and lean deeper in cold or soft-soil conditions. Under-building the base is the single most common cause of a surface that ruts and heaves.
Common questions
How deep should a paver base be?
It depends on the load. A patio or walkway that carries only foot traffic wants about 6 inches of compacted gravel base. A driveway that carries cars needs about 10 inches, and heavy vehicles or an RV need 12. Deeper base means more load capacity and better frost resistance.
How much gravel do I need for a paver base?
Multiply the area by the base depth in feet for the in-place volume, then add about 20 percent, since crushed gravel loses volume when it compacts. For a 200 square foot patio at 6 inches, that is roughly 2.2 cubic yards of base to order.
How much bedding sand do I need?
Plan on a 1 inch layer of coarse bedding sand over the compacted base. For 200 square feet that is about 0.6 cubic yards. Screed it flat and leave it uncompacted, because the pavers need to seat down into it as you level them.
What is the most common paver mistake?
Building the base too shallow to save on gravel. The surface looks perfect at first, then ruts, settles, or heaves within a season or two as the underbuilt base fails. When you are unsure about frost or soft soil, go deeper, not shallower.
Do I need fabric under the base?
Often, yes. A geotextile fabric between the soil and the gravel stops the two from mixing and keeps the base stable, especially over soft or clay soil or in a cold climate. It is cheap insurance against a base that pumps mud up into the gravel over time.
Sources: Base depth: patio/walkway ~6 in, driveway ~10 in, heavy ~12 in of compacted 3/4-minus gravel (Harbor Soils, NT Pavers) · 1 in uncompacted coarse bedding sand; order ~20% extra base for compaction. Engine version 1.0.0. Risk tier 1.