Most Hamilton and Burlington houses built before the 1990s came with a patio of 24 x 24 grey slabs behind the back door, and most of those slabs are now rocking, tilted toward the house, or sunk at one corner. That is not because slabs are a bad product. It is because they were usually set on a couple of inches of sand. This guide covers what patio stones are, how many you need, what they cost, and how to lay a slab patio that is still flat in ten years.
"Patio stones" means three different things
| Product | What it is | Installed, per sqft | Best for |
|---|---|---|---|
| Concrete patio slabs | Large flat precast squares, usually 24 x 24 or 24 x 30 in, about 2 in thick | $12 - $22 | Budget patios, paths, shed pads, rentals |
| Interlocking pavers | Smaller, denser concrete units that lock together with sand joints and an edge restraint | $22 - $40 | Long-lasting patios, curves, driveways |
| Flagstone | Natural stone slabs, irregular or cut | $30 - $60 | Natural look, cottage and heritage homes |
Large-format "slabs" sold by interlock makers, such as 24 x 24 or 24 x 36 inch architectural slabs, sit between the first two: thicker and denser than a hardware-store slab, and priced closer to pavers. For interlock, see our paver patio cost guide; for natural stone, the flagstone patio cost guide.
What patio slabs cost on the shelf
Standard grey 24 x 24 x 2 inch concrete slabs were listed at about $10.59 to $14.80 each at Home Depot Canada and Rona in October 2026, depending on the finish. That is roughly $2.65 to $3.70 per square foot for the slabs alone. They weigh about 75 to 80 lb each, so a pallet is a truck delivery, not a trunk load, and laying them is a two-person job.
How many patio stones do you need?
Divide the patio area by the area of one slab, then add 5 to 10 percent for cuts and breakage.
| Slab size | Covers | Per 100 sqft | 10 x 12 ft patio | 12 x 16 ft patio |
|---|---|---|---|---|
| 12 x 12 in | 1 sqft | 100 | 120 | 192 |
| 18 x 18 in | 2.25 sqft | 45 | 54 | 86 |
| 24 x 24 in | 4 sqft | 25 | 30 | 48 |
| 24 x 30 in | 5 sqft | 20 | 24 | 39 |
Counts are before the cutting allowance and assume tight joints. Plan the patio size in whole slabs where you can, for example 10 x 12 ft in 24 inch slabs, so you cut as few as possible. Our patio cost calculator works out a budget for any size.
How to lay patio stones that stay flat
- Book locates through Ontario One Call before you dig.
- Mark out and excavate. Dig deep enough for 6 to 8 inches of base, about an inch of bedding and the slab thickness. More on heavy clay.
- Lay geotextile fabric on the subsoil so the base does not sink into the clay over time.
- Build the base with 3/4 inch crusher run (Granular A), compacted with a plate compactor in lifts of about 2 inches. Slope it about 2 percent, or 1/4 inch per foot, away from the house.
- Screed the bedding: about an inch of concrete sand or stone screenings, levelled with rails and a straight board, following the slope of the base. Do not walk on it.
- Set the slabs from one straight edge, lowering each one into place rather than sliding it. Tap level with a rubber mallet and check with a 4 ft level as you go.
- Restrain the edges. Slabs walk outward without an edge. Use a paver edge restraint, a soldier row of pavers or a buried border. See our garden edging guide.
- Fill the joints with polymeric sand for a tight, weed-resistant joint, or stone dust or fine gravel for a softer look. Compact over the top with a pad under the plate so the slabs do not crack.
Patterns and sizes that work
- The straight grid. 24 x 24 slabs in a simple grid. Clean and modern, and the cheapest to lay because there are few cuts.
- The running bond. Rows offset by half a slab. Hides small differences in slab size and looks less rigid.
- Mixed sizes. 12, 18 and 24 inch slabs in a repeating ashlar pattern give a stone-like look from basic slabs.
- Slabs with a paver border. A border of darker pavers frames the slabs and acts as the edge restraint. Our patio ideas guide has more layouts.
- Stepping-stone paths. Single slabs set in lawn or gravel, about 24 inches apart centre to centre, for a path to the shed or garden.
Slabs or pavers?
Choose slabs for a budget patio, a path, a pad for a shed, or a rental where price matters most. Choose pavers for a patio you want to last 25 to 40 years, a curved shape, a driveway, or anywhere heavy loads go. Pavers lock together and spread load. Slabs sit side by side and rely entirely on the base. Our guide to choosing pavers and interlock vs concrete vs natural stone go further.
Fixing an old slab patio
If your slabs are rocking, sunk at the corners or draining toward the house, they can usually be lifted, the base rebuilt properly, and the same slabs relaid. Relevelling a settled area over a firm base runs about $6 to $14 per square foot reusing the same stones, and a full rebuild of the base runs about $18 to $32. See how to fix a sinking patio. If the patio slopes toward the foundation, fix that first, before water reaches the basement.
Frequently asked questions
How much do patio stones cost in Canada?
Standard 24 x 24 x 2 inch concrete slabs were about $10.59 to $14.80 each at Home Depot Canada and Rona in October 2026. Installed on a proper base, a slab patio runs about $12 to $22 per square foot.
How many 24x24 patio stones do I need?
One 24 x 24 slab covers 4 square feet, so you need 25 per 100 square feet, plus 5 to 10 percent for cuts. A 10 x 12 ft patio takes 30 slabs before the allowance.
Can I lay patio stones on sand only?
Not if you want them to stay flat. Sand alone washes out and moves with the clay below. Use 6 to 8 inches of compacted crusher run under about an inch of sand or screenings.
How much does a 24x24 patio slab weigh?
About 75 to 80 lb for a standard 2 inch thick concrete slab, based on Canadian store listings in 2026.
What should go between patio stones?
Polymeric sand for a tight joint that resists weeds and ants, or stone dust or fine gravel for a softer, more natural look that needs more weeding.
Which way should a patio slope?
Away from the house at about 2 percent, or 1/4 inch per foot, so water runs to the lawn or a drain instead of the foundation.
Are patio slabs cheaper than pavers?
Yes. A slab patio runs about $12 to $22 per square foot installed, against about $22 to $40 for interlocking pavers, but pavers last longer and handle heavier loads.