A poured concrete patio is one of the few hardscaping jobs where the material is cheap and the detailing decides everything. Ready-mix is usually the smallest line on the quote. Base preparation, joint layout, finishing, and curing are what determine whether the slab stays tight for fifteen years or cracks into random pieces by year three.
On a typical install, a broom-finished patio runs about $6 to $12 per square foot ($65 to $130 per square metre) in most US markets. The spread comes from access, site prep, and local labour, not from the concrete itself. This guide covers the general poured-slab job: thickness and mix design, subbase and reinforcement, joints, slope, curing, finishes, sealing, and repairs. Stamped work is a separate discipline with its own failure modes and stays out of scope.
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Slab Thickness, Strength, and Mix Design
For pedestrian use, a patio slab is normally 4 in (100 mm) thick. Step up to 5 to 6 in (125 to 150 mm) for vehicle loads, expansive clay, poorly compacted fill, or a heavy exposed-aggregate finish that removes the top few millimetres of paste.
Exterior flatwork in North America is typically specified at 3,500 to 4,000 psi (24 to 28 MPa) at 28 days. That comes mainly from holding the water-cement ratio near 0.45 to 0.50. The mix mistake we see most often is a crew adding water on site to make placement easier. Every extra 10 litres per cubic metre costs roughly 1 MPa of strength and increases shrinkage cracking. In Canada, CSA A23.1/A23.2 governs concrete materials and construction practice; in the US, ACI guidance and ASTM material standards are the usual references.
- Air entrainment. In freeze-thaw climates, 5 to 7 percent entrained air gives freezing pore water somewhere to expand. Without it, saturated concrete scales and spalls. Air-entraining admixtures are covered by ASTM C260/C260M, and Canadian and northern US suppliers assume entrainment unless told otherwise.
- Workability. A slump of 4 to 5 in (100 to 125 mm) places and finishes well. If the truck arrives stiff, ask for a plasticiser rather than a hose.
- Aggregate. 3/4 in (20 mm) coarse aggregate suits a patio. A 1-1/2 in (40 mm) stone in a 4 in slab leaves too little paste between stones for a clean broom finish.
Subbase, Vapour, and Reinforcement
Strip the topsoil, then place and compact 4 to 6 in (100 to 150 mm) of crushed granular base in lifts to about 95 percent of standard Proctor density. A plate compactor is enough for a patio. Leave the base uniform, damp but not muddy, and level to roughly 1/4 in (6 mm) over 10 ft (3 m).
Soil type changes the approach. Expansive clay, common in Texas, the Canadian Prairies, and inland Australia, swells and shrinks with moisture, so over-excavate and consider a vapour retarder as a capillary break. Sandy soils drain well but need thorough compaction and edge restraint. Fill or organic soils need engineered compaction and a geotechnical opinion before you pour.
On reinforcement: wire mesh laid flat on the ground does almost nothing. Reinforcement works only at mid-depth, chaired up before the pour.
- Welded wire mesh — 6×6-W1.4xW1.4 (152 x 152 mm, 10 gauge) is the common residential choice. Cheap, and easy to trample to the bottom.
- Rebar — #3 or #4 bar (10 or 13 mm) at 18 to 24 in (450 to 600 mm) centres holds position better and controls crack width more reliably.
- Macro synthetic fibre — helps against plastic shrinkage in hot, windy conditions. It does not replace joints and adds no structural capacity to a patio slab.
A vapour retarder under an exterior patio is optional, not automatic. It earns its place over expansive clay. It is not a substitute for drainage, and on a wet mix with rushed curing it can increase edge curling.
Joints, Slope, and Drainage
Concrete shrinks as it cures and it will crack. Joints do not prevent cracking; they decide where it happens. Control (contraction) joints are cut, tooled, or formed to about one quarter of the slab thickness, roughly 1 in (25 mm) on a 4 in slab, at 8 to 10 ft (2.4 to 3.0 m) spacing. That works out to about two to three times the slab thickness measured in feet.
- Keep panels square. Aim for a length-to-width ratio no worse than 1.5 to 1; long, narrow panels crack near the middle.
- No panel over 10 ft (3 m) on its longest side, whatever the slab thickness.
- Run joints off re-entrant corners where the patio steps or wraps a column, rather than across them.
Isolation (expansion) joints are different: full-depth, usually 1/2 in (12 mm) compressible material, wherever the slab meets something that will not move with it. That means the house foundation, steps, columns, pool shells, and driveways. A slab poured hard against a foundation wall will crack as it shrinks. Isolation joints are the cheapest insurance in the job.
Timing matters too. Saw-cut joints are normally cut 4 to 12 hours after finishing, once the concrete takes a saw without raveling. Waiting until the next morning is often too late in hot weather.
For drainage, the standard fall is about 1/8 in per ft, roughly 1 percent, away from the building. Less and water ponds; much past 2 percent and the patio feels awkward. Set the finished surface 4 to 6 in (100 to 150 mm) below the siding, direct runoff to a lawn or swale rather than the foundation, and extend downspouts well past the slab. In the Pacific Northwest, coastal New Zealand, and eastern Australia, a channel drain at the low edge is often worth the cost.
Curing and the Five Non-Stamped Finishes
Curing keeps moisture in the slab so cement keeps hydrating. Concrete reaches design strength at 28 days, but most of the surface durability is set in the first seven. Moist curing under plastic or wet burlap for 7 days gives the best result; a spray-applied membrane conforming to ASTM C309 is the practical choice for most patios. Occasional spraying on a hot day is not curing, and adding water during finishing weakens the top layer.
Hot, dry, windy conditions are hardest on a new slab. In an Australian summer or on a windy prairie afternoon, evaporation can outrun bleed water and cause plastic-shrinkage cracks within an hour of finishing. Windbreaks, shade, and a fog spray help.
Five finishes cover almost every patio that is not stamped:
- Broom — a stiff broom dragged through plastic concrete leaves fine parallel grooves. Cheapest, best wet grip, and it hides surface variation. It does hold dirt in the grooves.
- Smooth (hard trowel) — burnished to a dense sheen. Sharp looking, but genuinely slippery when wet. We would not specify it around a pool, on a shaded slope, or anywhere with regular rain or frost.
- Exposed aggregate — a surface retarder is applied and the top layer of paste washed away to reveal the stone. Excellent grip, hides hairline cracks and wear. Rougher on bare feet, and edge stones can loosen over time.
- Salt finish — rock salt broadcast onto the fresh surface and washed out after set, leaving shallow random pits. Inexpensive, subtle, and slip-resistant. The pits hold dirt, and fewer crews have done one.
- Saw-cut scoring — a decorative grid cut into the hardened slab within the first day. It mimics tile or flagstone, and the cuts can double as control joints if the spacing is designed correctly.
| Finish | Surface appearance | Slip resistance | Typical cost premium (USD) | Best suited to | Main drawback |
|---|---|---|---|---|---|
| Broom | Fine parallel grooves, matte | High | Included in base price | Most patios, pool surrounds, rental properties | Grooves trap dirt; needs periodic washing |
| Smooth (hard trowel) | Dense, burnished, reflective | Low when wet | +$1 to $2 per sq ft | Covered or sheltered patios, dry climates | Dangerous when wet or frosty; shows scratches |
| Exposed aggregate | Visible stone, deep texture | High | +$3 to $5 per sq ft | Garden settings, pool decks, high-traffic areas | Rough underfoot; edge stones can loosen |
| Salt finish | Subtle random pitting, low contrast | Medium to high | +$1 to $2 per sq ft | Contemporary patios, mild climates | Pits hold dirt; fewer crews offer it |
| Saw-cut scoring | Tile or flagstone grid | Unchanged from base finish | +$1 to $3 per sq ft | Formal layouts, entertaining areas | Extra labour; cuts must be sealed if exposed |
What a Concrete Patio Costs
Installed cost depends on area, access, excavation, base depth, finish, and local labour. Small patios carry a higher unit cost because mobilisation and formwork do not shrink with area; below about 150 sq ft (14 m²) the per-square-foot price climbs sharply.
The figures below include excavation, base, formwork, reinforcement, pour, finish, and basic cleanup. They exclude demolition, retaining walls, drainage works, and permits. Currency conversions are approximate and rounded, and metro pricing runs well above regional pricing.
| Item | Unit | USD | CAD (approx.) | AUD (approx.) | NZD (approx.) |
|---|---|---|---|---|---|
| Broom-finish slab, installed | per sq ft | $6 – $11 | C$8 – C$15 | A$10 – A$18 | NZ$11 – NZ$20 |
| Broom-finish slab, installed | per m² | $65 – $120 | C$88 – C$160 | A$110 – A$195 | NZ$120 – NZ$215 |
| Exposed aggregate finish | per sq ft | $9 – $16 | C$12 – C$22 | A$15 – A$26 | NZ$16 – NZ$29 |
| Salt finish | per sq ft | $8 – $13 | C$11 – C$18 | A$13 – A$21 | NZ$14 – NZ$24 |
| Saw-cut scoring | per sq ft | $7 – $13 | C$10 – C$18 | A$12 – A$21 | NZ$13 – NZ$24 |
| Penetrating sealer, applied | per sq ft | $1 – $3 | C$1.50 – C$4 | A$2 – A$5 | NZ$2 – NZ$5 |
| Crack injection (epoxy or polyurethane) | per linear ft | $40 – $80 | C$55 – C$110 | A$60 – A$125 | NZ$65 – NZ$135 |
| Slab lifting (polyurethane foam or mudjacking) | per project | $600 – $1,800 | C$820 – C$2,450 | A$900 – A$2,800 | NZ$980 – NZ$3,000 |
A 400 sq ft (37 m²) broom-finished patio typically lands between $2,400 and $4,400 in the US, with Canada running 20 to 35 percent higher on labour and Australia and New Zealand landing in a similar range once GST is included. The place to save money is a simple rectangular slab close to where the truck can park. The places not to save are base depth, reinforcement placement, and joint layout.
Sealing, Cracks, and Repairs
Sealing is worth doing, but the type matters more than the brand. Penetrating sealers (silane, siloxane, silicate) soak in, leave no film, and do not trap moisture, making them the safer choice for freeze-thaw climates; reapply every 3 to 5 years. Film-forming acrylics and urethanes deepen the colour, but they can peel and, if moisture gets underneath, blister or spall the surface. A film-forming sealer on a poorly drained slab is not worth the money. Either way, wait 28 days after the pour.
Beyond sealing, maintenance is about water and dirt: sweep or hose the surface, keep downspouts discharging away from the slab, and skip de-icing salt on new concrete. Sand is kinder in the first winter than rock salt.
Cracks fall into two useful categories. Shrinkage cracks are hairline, under 1/16 in (1.5 mm), roughly vertical in section, and often diagonal or corner-originating. They show up in the first weeks or months, usually because joints were spaced too far apart, curing was rushed, or the mix was too wet. They are unsightly but rarely structural, and sealing against water intrusion is often the whole fix. Structural cracks are wider than 1/4 in (6 mm), show vertical displacement between the two sides, or run parallel and close to a joint. Those point to a base problem such as poor compaction, erosion, a missing isolation joint, or tree roots, and need a professional assessment.
Repair options, roughly in order of severity:
- Routing and sealing — widen the crack, clean it, and fill with a flexible polyurethane sealant. For stable cracks that need waterproofing.
- Epoxy injection — rebonds the two faces. For cracks that are not actively moving and are wide enough to accept injection ports.
- Polyurethane injection — flexible and moisture-tolerant. Better for cracks that open and close seasonally.
- Slab lifting — foam injection or mudjacking to raise settled sections. Cheaper than replacement, but only worth it when the concrete itself is sound.
- Replacement — when the slab is badly cracked, displaced, and the base is compromised. Sometimes the honest answer.
Anything structural, or any drainage work involving a retaining wall or steps tied into the slab, is a job for a licensed contractor or engineer.
Frequently Asked Questions
How thick should a concrete patio be?
For normal foot traffic, 4 in (100 mm) is standard. Go to 5 or 6 in (125 to 150 mm) if the slab will see vehicle loads, sits on expansive clay, or is built over fill. Thicker slabs tolerate wider joint spacing, but keep panels under 10 ft (3 m).
How long before I can walk or drive on a new patio?
You can usually walk on a new slab after 24 to 48 hours and place furniture after about 7 days. Vehicles should stay off for at least 7 days, and ideally 28 days for anything heavy. Cold, wet weather extends every one of those windows.
Do I need rebar, or is wire mesh enough?
For a patio on a well-compacted base, wire mesh chaired at mid-depth is adequate for crack-width control. Rebar on an 18 to 24 in (450 to 600 mm) grid holds position better and is worth the extra cost on thicker slabs or expansive soils. Either way, reinforcement lying on the ground does nothing.
Why did my patio crack in the first year?
The usual causes are joints spaced too widely, rushed curing, or too much water in the mix. Hairline cracks that stay stable are shrinkage cracks and are mostly cosmetic. Cracks wider than 1/4 in (6 mm), or with one side higher than the other, point to a base problem and need a professional assessment.
Is a concrete patio cheaper than pavers?
Usually yes on a cost-per-square-foot basis, and it needs less ongoing maintenance because there are no joints to sweep or weeds to pull. Pavers win on repairability: a cracked paver can be lifted and replaced, while a cracked slab is patched or replaced by section.
How often should a concrete patio be sealed?
A penetrating silane or siloxane sealer typically lasts 3 to 5 years, while a film-forming acrylic may need attention every 1 to 3 years, especially in coastal or high-UV locations. Wait at least 28 days after the pour, and never seal over a wet slab.
About the Author
Wartaholic Writer is a contributing editor at Wartaholic, covering outdoor living, hardscaping, and patio design. Articles are researched against manufacturer documentation, published industry standards, and hands-on installation practice, then fact-checked before publication.
Last updated: September 2026