How Deep Should the Base Be Under Pavers?

Belgard’s installation guide states a minimum compacted base of 4 in under a patio. Unilock’s project planning guide gives 6 to 8 in for a patio. Which depth is right? This guide sets each number beside the brand and use that states it, because the figures do not merge into one.

What Base Depth Do Paver Makers State?

Each maker states base depth by application, and the numbers differ between brands and even between two Unilock pages. Belgard gives minimums on page 6 of its product installation guide: 4 in for sidewalks, patios and pedestrian areas, 6 in for residential driveways and 8 in for a parking lot or residential street. Pages 6 and 7 were read on a third-party document viewer, not on belgard.com.

Unilock gives ranges. Its Project Planning Guide lists typical base thickness of 6 to 8 in for patios and walkways, 6 to 12 in for pool decks and 10 to 14 in for driveways. Its do-it-yourself base preparation page says 4 to 6 in for pedestrian walkways and 8 to 12 in for driveways.

The Concrete Paver Calculator counts pavers, bedding sand and edge restraint from your area. It does not size the base, so base depth comes from your paver maker’s guide.

How Far Apart Are the Stated Depths?

For a patio, the stated figures run from 4 in (Belgard’s minimum) to 8 in (the top of Unilock’s guide range). For a driveway they run from 6 in (Belgard’s minimum) to 14 in (the top of Unilock’s guide range). The chart draws every bar at one scale.

The types of statement differ. Belgard’s figures are labelled minimums. Unilock’s guide calls its figures typical thicknesses, and its DIY page calls its figures guidelines. Because a minimum and a typical range are different kinds of statement, this article never averages them.

Polycor makes natural stone pavers (Indiana limestone), not concrete ones. Its installation guide gives a general minimum of 4 in (100 mm) after compaction for sidewalks, patios and pedestrian areas over well-drained soils. For driveways, follow your paver maker, your contract or your local rule.

What Sits Between the Base and the Pavers?

A bedding layer of about 1 in sits on the compacted base, and the pavers sit on the bedding. Belgard lists the bedding layer as 1 in nominal. Unilock’s guide describes a 1 in bed of coarse sand or 1/8 in open-graded chip, placed directly on the compacted base.

Belgard lists a minimum paver thickness of 2 3/8 in for pedestrian areas and driveways and 3 1/8 in for street or parking use. Its page 7 steps call for an uncompacted bedding sand layer screeded level, and Unilock’s DIY page says not to compact the bedding layer. Unilock’s guide names 3/4 in crusher run or 3/4 in clear stone for the gravel base.

Unilock’s DIY page advises against stone dust and limestone screenings because they have too many fines. It names a small chip stone, such as ASTM #9s or clear 1/8 in chip, as an alternative to sand. For edges, Belgard requires rigid concrete edge restraints for commercial or vehicular use, while Unilock’s guide says edge restraints must be spiked into the compacted base.

How Deep Do You Dig, and How Thick Is Each Layer?

Belgard’s installation steps say to excavate a minimum of 8 in below finished grade. Unilock’s slope page says to dig down approximately 8 in. Unilock’s guide adds that excavation depth depends on soil type: clay needs a deeper dig and sandy soil needs less.

As arithmetic, the dig for a layered build is the base plus 1 in of bedding plus the paver thickness. With Belgard’s 4 in pedestrian minimum and a 2 3/8 in paver, that is 4 + 1 + 2.375 = 7.375 in. With the 6 in driveway minimum and a 2 3/8 in paver, it is 6 + 1 + 2.375 = 9.375 in. These sums are not stated by any source read; Belgard’s own figure is the 8 in minimum.

Layer thickness differs too. Belgard says to compact in 2 to 4 in lifts. Unilock’s guide says layers 2 to 3 in thick, and its DIY page says 3 to 4 in and notes that most traditional plate compactors will not compact more than 4 in of base. Unilock’s slope page gives a 9 in base in 3 in layers as its example. None of the pages read gives a number of compactor passes.

On clay, Unilock’s DIY page says bases are generally dug deeper to help drainage, and it calls a layer of geotextile under the granular base good practice. Polycor’s natural stone guide gives 6 to 8 in for clayey or silty soil and 4 to 6 in for sandy or gravelly soil.

How Much Should a Paver Surface Slope?

Belgard states a minimum surface slope of 2% for drainage, while Unilock’s slope page says patios may be sloped to a maximum of 2%. One is a floor and the other is a ceiling, so the two meet at 2% and then point in opposite directions. Follow your own paver maker’s figure.

Other pages read give slopes as well. Unilock’s DIY page calls 1% to 2% adequate for drainage, and Belgard’s page 7 says to slope the subgrade 1 to 2%. Unilock’s slope page allows walkways to slope 5% if the walking surface is non-slip. Polycor’s natural stone guide gives a minimum of 3/16 in per foot, which is 3/16 / 12 = 1.56% by arithmetic. For concrete rather than pavers, see how to slope a concrete patio.

How Much Base Does a 12 by 10 Foot Patio Need?

The tool’s default 12 by 10 ft patio needs 40 cu ft of compacted base at 4 in, 60 cu ft at 6 in and 80 cu ft at 8 in. These are arithmetic on compacted thickness, not sourced figures.

1. Area. 12 x 10 = 120 sq ft.
2. Pavers. An 8 x 4 in paver face is 32 sq in, or 0.2222 sq ft. Then 120 / 0.2222 = 540, and 540 x 1.10 for 10% waste = 594 pavers.
3. Bedding sand. 1 in is 1/12 ft, so 120 x 1/12 = 10 cu ft, or 10 / 27 = 0.37 cu yd.
4. Base at 4 in. 120 x 4/12 = 40 cu ft, or 40 / 27 = 1.48 cu yd.
5. Base at 6 in. 120 x 6/12 = 60 cu ft, or 60 / 27 = 2.22 cu yd.
6. Base at 8 in. 120 x 8/12 = 80 cu ft, or 80 / 27 = 2.96 cu yd.

These are volumes at compacted thickness. No source read gives a factor for loose material becoming compacted, so the amount to order is more than these numbers. For a poured slab instead of pavers, see how thick a slab should be. A heavy load is its own question: see putting a hot tub on pavers.

FAQs About Paver Base Depth

Sources and Further Reading

This page reports what named paver makers state, not a design for your site. Base depth depends on the paver maker, the load and the soil, so follow your own paver guide and dig to its depth. Reviewed for accuracy by Prof. Dr. Khalil Mudassar, PhD. Last updated 2026-10-21.