Why the number moves so much
Three things set the rate, and none of them is floor area.
Mechanical density. A bedroom has a light, a couple of outlets and a heat register. A kitchen has plumbing supply and drain, a gas line, a dedicated range circuit, a dishwasher circuit, a fridge circuit, a fan vented outside and cabinetry built to the millimetre. Same square footage, entirely different job. This is why kitchens and bathrooms sit at the top of every table on this page and why bedrooms and basements sit at the bottom.
Finish level. The structural shell of a room is a small fraction of its cost. What you put in it is most of it. Our flooring guide puts laminate at $3 to $7 a square foot installed and tile at $7 to $22 — a threefold spread on the identical floor.
Access and condition. A third-floor bathroom in a 1920s house with no side yard costs more than the same bathroom on a slab in a 2005 subdivision. Knob-and-tube wiring, a basement with no headroom, a driveway that will not take a bin — none of that shows up in a square-foot figure and all of it shows up on the invoice.
By project: the real ranges
Rooms and whole-house work
| Project | Ontario range | Guide |
|---|---|---|
| Finished basement | $30–$130 per sq ft | Basement renovation |
| Kitchen, mid-range | $30,000–$55,000 ($40,000–$75,000 GTA) | Kitchen renovation |
| Bathroom, mid-range | $15,000–$30,000 | Bathroom renovation |
| Home addition | $200–$650 per sq ft | Home addition |
| Garden suite or laneway house | $400–$650 per sq ft | Garden suites |
| Detached garage | $90–$140 per sq ft | Detached garage |
Surfaces and finishes
| Work | Ontario range | Guide |
|---|---|---|
| Drywall, supplied and installed | $2.00–$4.50 per sq ft | Drywall |
| Laminate flooring | $3–$7 per sq ft | Flooring |
| Hardwood flooring | $9–$18 per sq ft | Flooring |
| Tile flooring | $7–$22 per sq ft | Flooring |
| Interior painting, one bedroom | $450–$800 | Interior painting |
| Interior painting, three-bedroom house | $6,500–$13,000 | Interior painting |
Outside the house
| Work | Ontario range | Guide |
|---|---|---|
| Asphalt shingle roof | $5.50–$9.50 per sq ft of roof area | Roof replacement |
| Vinyl siding | $3–$14 per sq ft | Siding |
| Fibre cement siding | $8–$20 per sq ft | Siding |
| Replacement window | $500–$1,000 each, $12,000–$35,000 whole house | Windows |
| Pressure-treated deck | $30–$65 per sq ft | Decks |
| Pressure-treated fence | $30–$65 per linear foot | Fences |
| Asphalt driveway | $7–$13 per sq ft | Driveways |
| Interlock driveway | $18–$40+ per sq ft | Driveways |
| Eavestrough, 5-inch | $8–$15 per linear foot | Eavestrough |
| Inground pool | $40,000 vinyl to $200,000+ concrete | Pools |
Systems and repairs
| Work | Ontario range | Guide |
|---|---|---|
| Gas furnace, installed | $4,500–$7,000 | Furnace |
| Cold-climate heat pump | $9,000–$18,000 | Heat pumps |
| Central air conditioning | $4,000–$9,500 | Air conditioning |
| Water heater, gas tank | $2,100–$5,500 | Water heaters |
| Electrical panel, 100A to 200A | $2,500–$5,000 | Panel upgrade |
| Attic insulation, blown-in | $1,800–$3,200, with $1,250 back | Attic insulation |
| Basement waterproofing, interior | $80–$150 per linear foot | Waterproofing |
| Basement waterproofing, exterior | $150–$300 per linear foot | Waterproofing |
| Foundation crack injection | $500–$1,500 per crack | Foundation repair |
| Backwater valve, retrofit | $1,800–$4,200 | Sump pumps and valves |
| Mould remediation | $3.50–$5.00 per sq ft of affected material | Mould removal |
| Asbestos abatement | $8–$15 per sq ft | Asbestos removal |
Whole-house benchmarks
For the three biggest decisions, the per-square-foot comparison is genuinely useful — because you are comparing like with like.
| Approach | Toronto and GTA, per sq ft |
|---|---|
| New custom home construction | $350–$450 typical, $450–$650 mid-range, $650–$900+ at the top |
| Full gut renovation of an existing house | $450–$550+ |
| Addition onto an existing house | $350–$650 |
Read that table twice, because it contains the least intuitive fact in Ontario renovation: adding on and gutting both cost as much per square foot as building new, or more. You are not saving money by keeping the house. You may be saving the land, the location, the trees and the disruption of moving — all real — but not the rate.
What a per-square-foot number is useful for
Three legitimate uses, and one that gets people into trouble.
Sanity-checking a single quote. If a contractor quotes $180,000 for a 600 square foot basement, that is $300 a square foot against a published range of $30 to $130. The number does not tell you the quote is wrong — but it tells you to ask what is in it.
Comparing two quotes for the same scope. Divide both by the same area and the difference becomes visible.
Setting a first budget before you have drawings. Take the midpoint, add 15 per cent, and you have a number good enough to decide whether the project is possible at all.
The trap: applying a rate from one project type to another. A homeowner who has just finished a basement at $60 a square foot and assumes the kitchen will land near it is about to be badly surprised. Rates do not travel between rooms.
Reading a quote against these numbers
| What you see | What to ask |
|---|---|
| A single lump sum with no breakdown | Labour, materials, permit, disposal as separate lines — without them the rate is unverifiable |
| A per-square-foot rate with no area stated | Which area: floor, wall, roof surface? Roofing is quoted on roof area, not floor area, and the two differ substantially |
| A rate well below every published range | What is excluded. Usually permits, disposal, finishes, or restoring what gets opened up |
| A rate well above every published range | What is included that others leave out. Sometimes the answer is good, sometimes it is a mark-up |
| No contingency line | Add 10–20% yourself. Every builder we read recommends it |
| No allowance for finishes | Which fixtures, tile and cabinetry are assumed, at what price point |
One rule that applies to all of them: under Ontario’s consumer rules, where a contract includes an estimate the final price cannot exceed it by more than ten per cent unless you agreed to additional work or a new price. That protection only exists if there is a written estimate to measure against. Your rights under an Ontario renovation contract covers it properly.
Frequently asked questions
No, and this catches people out. Roofing is quoted on roof surface area, which is larger than the footprint because of pitch and overhangs, and larger again on a complex roof with valleys and dormers. Ask which area a quoted rate is applied to before comparing two roofing prices.
Almost always because they are not the same renovation. Different finish allowances, different assumptions about what gets opened up and restored, and different treatment of permits and disposal. Give every company the same written scope and the same list of finishes, and the spread narrows dramatically.
Ten per cent on straightforward work and closer to twenty on anything that involves opening up an older house. Every Ontario builder we read recommends 10 to 20 per cent, and the most common surprises — electrical service, HVAC capacity, drainage, and repairs found behind walls — are precisely the ones you cannot price in advance.
Per square foot, building new is usually cheaper. New custom construction in the GTA runs about $350 to $450 per square foot, while a full gut renovation runs $450 to $550 or more and an addition $350 to $650. Renovating buys you the land, the location and the mature trees, not a lower rate.
Mechanical density and finishes. A kitchen carries plumbing supply and drain, a gas line, several dedicated electrical circuits, a vented exhaust fan and cabinetry built to close tolerances. A bedroom has a light, outlets and a heat register. The floor area is identical and the work is not remotely comparable.
There is no single figure, and any page offering one is averaging across projects that have nothing in common. A finished basement runs $30 to $130 per square foot, a home addition $200 to $650, and a kitchen works out to roughly $400 to $700 on the same floor area. Use the rate for your specific project type rather than a blended average.
Sources
- All project ranges above are drawn from Carpenter Bee’s own Ontario cost guides, each linked in the tables and each carrying its own sources and check dates
- Whole-house benchmarks: Toronto design-build and custom-build firms Lighthaus Built, Xavieras and Andare Homes, checked 19 September 2026
- Government of Ontario — your rights when starting home renovations or repairs, including the ten per cent estimate rule, ontario.ca, checked 19 September 2026
These are planning bands, not quotes. Prices move with region, season, finish level and the condition of the building. Carpenter Bee does not set prices and does not perform work.
More Carpenter Bee guides
Keep reading
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Published cost guides put a finished basement in Ontario at roughly $30 to $130 per square foot in 2025-2026. Here is what sits behind that range.
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