How much does a home addition cost in Quebec and Canada?
Foundation, shell and finishing: a price per square foot that distinguishes a closed shell from a turnkey.
Your project
Is it new construction or a renovation?
In new construction, there is nothing to remove.
The price of a home addition is calculated per square foot, and depends mostly on the foundation, the level of finish and the rooms it contains. The calculator prices the foundation, the shell (structure, roof, siding, windows) and the interior finishing, at Quebec rates.
What changes the price of a home addition
- Type of addition
- A ground-level extension, a second-storey addition or a garage have neither the same foundation, nor the same structure, nor the same constraints.
- The base
- Screw piles, slab on grade or a concrete foundation with basement: the price gap is considerable.
- Shell or turnkey
- A closed shell (structure, roof, windows, siding) costs a fraction of a finished, livable addition.
- Bathroom or kitchen
- A room with plumbing costs much more per square foot than a bedroom.
- Tying into the house
- Opening the existing wall and tying in the roof, heating and electrical are part of the price.
What the estimate includes
- The chosen foundation, excavation and backfill
- Structure, roof, siding and windows
- Interior finishing (insulation, drywall, floors, paint) for turnkey
- Plumbing, electrical and heating, by licensed tradespeople
- Plans, permit, labour at the CCQ rate and a general contractor’s normal margin
Frequently asked questions
How much does a home addition cost in Quebec and Canada?
A 20 × 16 ft (320 sq ft) addition costs $119,200 to $152,400 in Quebec in 2026: poured concrete foundation, turnkey without a bathroom, engineered wood siding, pitched roof. An added storey or a bathroom changes the budget. Amount before taxes, calculated line by line by qcalculatrice.com at Quebec prices (Québec — grille 2026 v2.2), range verified on September 18, 2026. This is an estimate, not a quote: the calculator redoes it for your home.
Do I need architect’s plans for an addition?
An addition needs plans for the permit; a technologist or an architect prepares them. A second-storey addition almost always requires an engineer’s opinion on the existing structure.
How long does an addition take?
Two to four months of work for a turnkey extension, not counting the plans and permit, which often take just as long.
Add a storey or extend at ground level?
Ground level costs less per square foot if the lot allows it. A storey avoids losing yard, but means checking the foundation and living through the work overhead.
Is this a firm price?
No. It is an estimate calculated for your project, made to set a budget and compare quotes. Only a contractor who has seen the house and the plans can sign a price.