Interlock Install Process · 2026

How We Install an Interlock Patio or Driveway in Ontario

By Riaad, Owner & Project Manager · ICPI Certified Installer · Last updated May 19, 2026

Interlock paver driveway under installation with 3/4-clear stone base and geotextile

The seven-stage ICPI install process we run on every interlock patio and paver driveway in Hamilton, Burlington, Oakville, and across the Golden Horseshoe: excavate to subgrade, lay non-woven geotextile, compact a 6 to 10 inch 3/4-clear stone base in 2-inch lifts, screed 1 inch of HPB bedding sand, lay pavers, install aluminum edge restraint, sweep and activate polymeric sand. Total install: 3 to 7 days for residential. This is the same spec sheet we hand every crew lead on day one.

Why the install process matters more than the paver

Premium Unilock and Techo-Bloc pavers fail in 3 to 5 years on a bad base. Generic builder-tier pavers last 25 years on a properly compacted 3/4-clear base with geotextile and proper edge restraint. The paver is the visible 15 percent of the install; the base, fabric, sand, and edge restraint are the 85 percent that determine whether the patio still looks new after 10 Hamilton winters. This guide walks through the full process so homeowners know what to look for on their own install.

Step 1: Excavate to subgrade

Excavate 12 inches for patios, 14 to 16 inches for driveways, and 10 inches for low-traffic walkways. Remove all topsoil, roots, and unstable fill down to competent clay or compacted till subgrade. The exposed subgrade is sloped at 2 percent (1:50) away from the house per Ontario Building Code grading rule, set with a laser level and grade stakes. Photograph the subgrade before any base goes in: this is the audit point that catches most contractor shortcuts.

Common subgrades across our service area: Halton-Till clay (Burlington, Oakville, Milton), Queenston shale (Hamilton Mountain), sandy loam (Aldershot, Bronte), shallow bedrock (Ancaster village, Dundas village).

Step 2: Lay non-woven geotextile fabric

Roll Mirafi 140N (or equivalent non-woven needle-punched geotextile) across the entire subgrade with 12-inch overlaps at seams and 6 inches turned up the sides of the excavation. Geotextile separates subgrade clay from base aggregate, preventing fine particles from migrating up into the base where they cause progressive settlement.

Geotextile is the cheapest insurance against long-term settlement. A 12 x 12 ft patio uses about $40 of fabric. Skipping it adds zero to install time but causes the base to lose drainage capacity over 5 to 8 years.

Step 3: Install 3/4-clear stone base in 2-inch lifts

Spread 3/4-clear crushed limestone (open-graded angular aggregate, no fines) in 2-inch lifts. Compact each lift to 95 percent Proctor density with a 3000 to 5000 lbf plate compactor. Total compacted base depth:

  • Patios on stable subgrade: 6 inches
  • Driveways: 8 inches
  • Heavy clay or poor drainage (Milton subdivisions, Stoney Creek mountain): 10 inches
  • Commercial / RV / boat trailer: 12 inches

Open-graded 3/4-clear drains roughly 10 times faster than traditional Granular A road base. The voids in the aggregate let groundwater move through rather than freeze inside the base, which is what causes heaving in Hamilton-area freeze-thaw cycles. ICPI Tech Spec 17 covers permeable interlocking concrete pavement design where the base also serves as a stormwater storage layer; for residential installs, the 3/4-clear base provides drainage benefits without permeability complexity.

Step 4: Screed 1 inch of HPB bedding sand

Place two 1-inch screed pipes parallel across the compacted base. Spread HPB (high-performance bedding) sand or ASTM C33 concrete sand between the pipes. Pull a 2x4 across the pipes to screed a uniform 1-inch layer. Remove the pipes and back-fill the gaps by hand. Do not compact bedding sand before laying pavers; the sand must remain loose for the pavers to set into.

Sand depth is critical. Less than 3/4 inch and the pavers do not lock into place; more than 1 1/4 inch and the sand layer becomes a failure plane under wheel load.

Step 5: Lay pavers in pattern

Start from a fixed line (typically a string aligned to a structure or a planned focal point). Place each paver hand-tight against its neighbors with 2 to 3 mm joint spacing. Cut perimeter pieces with a diamond-blade wet saw to fit edges, curves, and obstacles. Maintain pattern integrity through every course; never adjust the pattern mid-row to compensate for a measurement error.

Paver thickness matters for the application:

  • Patios and walkways: 45 to 60 mm (Unilock Holland Premier 60 mm is the workhorse spec)
  • Driveways: 70 to 80 mm (Techo-Bloc Industria 80 mm or Unilock Camelot 70 mm)
  • Commercial / heavy load: 80 to 100 mm

Using 60 mm pavers on a driveway is the #1 cause of premature paver failure we see on competitor work in Hamilton and Burlington.

Step 6: Install aluminum edge restraint

Place aluminum edge restraint along all perimeter edges of the install. Drive 8-inch galvanized spikes through the restraint into the compacted base every 12 inches. Aluminum lasts 30+ years; do not use plastic edge restraint on driveways or any commercial install.

Edge restraint prevents lateral paver spread under freeze-thaw and wheel load. Pavers without proper edge restraint fail within 3 to 5 winters in our climate; we have ripped out plenty of 5-year-old patios where the edges have walked away by 1 to 2 inches.

Step 7: Sweep and activate polymeric sand

Sweep dry polymeric sand (Techniseal HP NextGel, Alliance Gator Maxx G2, or SRW Permasand) into joints on a dry day. Plate-compact to settle the sand. Top up and re-sweep until joints sit 3 to 4 mm below the paver chamfer. Blow the paver surface completely clean with a leaf blower before activation; any residual sand on the surface will activate as white haze.

Mist-activate with low-pressure water in 4 to 6 passes over 20 minutes, letting water absorb between passes. Keep dry for 24 hours minimum after activation. Full cure: 7 to 30 days depending on temperature and humidity. Wait 60 to 90 days before sealing. For the full polymeric sand playbook, see our 2026 polymeric sand cure time guide.

Real install timelines

Project Install days 2026 cost range
100-150 sq ft patio2-3 days$1,800-$4,200
300 sq ft patio3-5 days$5,400-$8,400
600 sq ft pool deck5-8 days$11,000-$18,000
2-car interlock driveway (400-600 sq ft)5-7 days$28,000-$48,000

Warranty and inspection

Every Seven Stones install carries a 5-year workmanship warranty plus full manufacturer warranties on Unilock (lifetime) and Techo-Bloc (lifetime) pavers. We photograph subgrade, fabric, base depth, and finished install at each stage and provide the photos to the homeowner at handoff. Final inspection includes a 1-year follow-up visit for joint top-up if needed.

References

Free on-site quote across Halton. Hamilton, Burlington, Oakville, Milton, Mississauga, Ancaster, Dundas, Stoney Creek, and Waterdown. Get a free quote