How should a paver patio base be built and installed?

The layers, bottom to top

A sand-set paver patio is a flexible pavement. Each layer has a job.

Layer	What it does	Guidance
Compacted soil (subgrade)	Supports everything	Compact to at least 98% standard Proctor density (ASTM D698)[1]
Geotextile (optional)	Keeps soil from mixing into the base	Used on wet, clay or freeze-thaw soils; at least 12 in overlap downslope[1]
Aggregate base	Main structural layer	Crushed, dense-graded stone; 4 in minimum for patios[1]
Bedding sand	Seats the pavers	Concrete sand (ASTM C33) screeded to nominal 1 in, uncompacted[1][2]
Pavers	Wearing surface	Compacted into the sand, then joint sand added[1]
Edge restraint	Stops pavers from spreading	Concrete, plastic, steel or aluminum edging[2]

How deep should the base be?

Use	Minimum compacted base	Source
Patios and walks, well-drained soil	4 in	CMHA[1]
Walks	4 to 6 in	ICPI[2]
Residential driveways	6 in (CMHA); 6 to 8 in (ICPI)	[1][2]
Clay pavers, patios and walks	4 in	BIA[3]

CMHA adds that colder climates and continually wet or weak soils need thicker bases^[1]. For preliminary design, BIA suggests adding 4 inches of aggregate under driveways on clay or silt soil^[3].

The base goes down in lifts, not all at once. CMHA calls for 4 to 6 inch lifts with a 7,000 lbf reversible plate compactor, and thinner lifts with a smaller 5,000 lbf machine. Do not place base on frozen soil or use frozen base material^[1]. The finished base surface should be within plus or minus 3/8 inch under a 10 foot straightedge^[1].

Step by step

1. Call 811 first. The free national before-you-dig service marks buried utilities with paint or flags. Contact it a few business days before digging^[4].
2. Lay out and set grade. Stake the area and set string lines for slope. CMHA says paver surfaces should slope at least 1.5%^[1]. BIA recommends at least 1/4 inch per foot (2%) for clay pavers^[3]. Slope away from the house.
3. Excavate and compact the soil. Dig to the depth of base plus sand plus paver. Remove roots, organic soil and debris, then compact^[1].
4. Add geotextile if needed. Over clay, wet ground or in freeze-thaw areas^[1].
5. Place and compact the base in lifts. Fix low spots in the base with more base material, never with sand^[2].
6. Install edge restraints. Many go in before the sand; some plastic and metal edging goes in after the pavers. The base should extend past the edge, and on home projects the stakes should sit no more than 10 inches from the base perimeter^[2]. CMHA calls for at least 1 inch of vertical restraint against the side of the paver^[1].
7. Screed the bedding sand. Spread concrete sand and screed it to an even, uncompacted 1 inch^[1]. ICPI's range is 1 to 1 1/2 inches, and it should not be used to fill dips^[2].
8. Lay the pavers. Pull from 3 or 4 bundles at once to blend color. Keep joints 1/16 to 3/16 inch^[1]. Cut edge pieces with a saw or splitter, and control the dust: CMHA notes it contains respirable crystalline silica^[1].
9. Compact the pavers. Use a plate compactor of at least 5,000 lbf at 75 to 90 hertz, with at least two passes^[1].
10. Fill the joints. Sweep in dry joint sand and compact again until joints are full, which may take two or three passes^[1]. Stabilized (polymeric) joint sand is optional and can help where joint sand washes out^[1].

HomeGuide estimates a two-person crew lays about 100 square feet of pavers a day, not counting prep^[5].

Myths and shortcuts that cause sinking

• "Stone dust makes a good bedding layer." ICPI says stone dust and screenings should not be used for bedding because they can carry too many fines^[2].
• "Mason sand is fine under pavers." ICPI says mason sand drains slowly and is unstable as bedding^[2]. It can be used in the joints^[2].
• "Use extra sand to level the low spots." Thick sand pockets settle. Both CMHA and ICPI say to fix the base, not pad it with sand^[1][2].
• "Edging is optional." CMHA calls edge restraints a key part of the system; without them pavers drift and joints open^[1].
• "Compacting the pavers will crack them." Compaction is how pavers lock together. ICPI notes a protective pad on the compactor plate can reduce the risk of marking paver faces^[2].

What a finished job should look like

• Pavers about 1/8 to 1/4 inch above surrounding edges or drains to allow for minor settling^[1].
• No more than 1/8 inch lippage (height difference) between neighboring pavers on walking routes^[1].
• Surface within 3/8 inch under a 10 foot straightedge^[1].
• Joint lines within 1/2 inch over 50 feet of string line^[1].

If a section sinks later, pavers can be lifted, the base repaired and the same units relaid. See fixing sunken pavers.

When to call a pro

• The patio sits next to the house and the yard drains toward it.
• The soil is clay, stays wet, or is on a slope, where base depth and drainage need design.
• The job includes a driveway, steps or a retaining wall.
• You want independent installers to bid a written base spec (depth, material, compaction, edging) so the bids compare.