Prices checked September 2026. The per-square-foot figure covers framing, insulation, drywall, flooring, lighting, doors and paint. What makes budgets blow up is usually outside it: water getting in, a ceiling too low to meet code, or a bathroom that needs the concrete floor cut open for drains. Get those answered before you compare finish levels.
How much does it cost to finish a basement per square foot in the GTA?
2025 and 2026 price guides from at least six GTA and Ontario renovation contractors put a basic finish at about $35 to $60 per square foot, a mid-range finish at $55 to $80, and high-end work or a legal suite at $80 to $150. Most completed projects with a bathroom land between $55 and $100 per square foot. These are contractor-published figures, not a survey, so treat them as a range to test quotes against.
| Item | Low | Typical | High | What drives it |
|---|---|---|---|---|
| Basic finish, per sq ft | $35 | $45–$55 | $60 | Open plan, laminate or vinyl floor, standard lighting |
| Mid-range finish, per sq ft | $55 | $60–$75 | $80 | Rooms, pot lights, better flooring, a bathroom |
| High-end or legal suite, per sq ft | $80 | $90–$120 | $150 | Kitchen, fire separation, separate heating and entrance |
| 1,000 sq ft basement, basic to mid | $35,000 | $50,000–$75,000 | $85,000 | Finish level, number of rooms |
| Three-piece bathroom added | $10,000 | $15,000–$25,000 | $35,000 | Existing rough-in or cutting the slab |
| Bathroom rough-in only | $3,500 | $5,000 | $7,000 | Distance to the main drain |
| Interior waterproofing | $2,000 | $5,000–$10,000 | $15,000 | Length of wall, drainage membrane, sump pit |
| Exterior waterproofing | $10,000 | $15,000–$30,000 | $50,000+ | Excavation depth, landscaping and decks in the way |
| Egress window, each | $1,500 | $2,500–$5,000 | $8,000 | Cutting the foundation, window well |
| City of Toronto permit, basement finish | $214.79 minimum | About $460 for 800 sq ft | Higher for a suite | $6.20 per square metre in 2026 |
How is basement finishing priced on Doyo?
Basement Finishing on Doyo is priced by written quote, like Kitchen Renovation and Bathroom Renovation. A contractor visits, looks at the space and sends a line-by-line quote in the app. You pay a deposit when you accept it, and Doyo holds that deposit until you confirm the work is done. Part of the contractor’s payment is held back for a warranty period after completion, so there is still money on the table if something needs putting right.
Describe the space when you book: rough measurements, photos, whether it has ever been wet, what you want (a family room, a bedroom, a bathroom, a rental suite) and your timeline. Ask the contractor to confirm in the quote which permits the job needs and who applies for them.
How much does a legal basement apartment cost in Ontario?
A legal secondary suite typically costs 30% to 50% more than an ordinary finish of the same size, and GTA contractors commonly quote $80 to $150 per square foot, which puts many suites at $90,000 or more. The extra goes into fire separation between units, smoke and carbon monoxide alarms, egress windows or a separate entrance, sound insulation, a kitchen and sometimes separate heating. Toronto requires a building permit with full drawings for a secondary suite, and Newmarket requires accessory dwelling units to be registered.
What do permits cost for a basement in Toronto and Newmarket?
Permit fees are a small part of the budget. The City of Toronto’s 2026 fee for finishing a basement in a house is $6.20 per square metre, with a $214.79 minimum, so an 800 square foot (74 square metre) basement is about $460 before drawings. The Town of Newmarket’s 2026 schedule sets a flat $1,000 fee for an accessory dwelling unit inside an existing house and $500 for each below-grade entrance, and a one-time registration fee of $268.93 applies to additional residential units. Drawings by a designer with a Building Code Identification Number (BCIN) typically cost more than the permit itself.
What changes the cost of finishing a basement?
- Water. Any sign of dampness, efflorescence or past flooding needs fixing first; finishing over a wet wall wastes the whole budget.
- Ceiling height. Low ceilings may mean moving ducts or, at the extreme, underpinning or lowering the floor, which in Toronto needs a permit and an engineer and costs tens of thousands of dollars.
- Bathrooms and kitchens. Plumbing is the most expensive room work, especially if the slab has to be cut to reach the drain.
- Egress. Bedrooms and suites need a window or door people can escape through; cutting a larger opening in the foundation is costly.
- Legal suite or not. Fire separation, alarms, sound insulation and a second entrance add significantly.
- Finish level. Flooring, pot lights, built-ins and trim choices move the per-square-foot price more than people expect.
- Mechanical upgrades. An older panel may need more capacity, and the furnace may need extra ducts or a separate zone.
How do I avoid being overcharged for a basement renovation?
- Get at least two or three written quotes on the same scope, broken down by trade, with allowances for flooring and fixtures shown in dollars.
- Keep the deposit small. Ontario recommends down-payments of no more than 10%, and any renovation contract over $50 must be in writing.
- Know the 10% rule. The final price cannot be more than 10% over the estimate unless you agree to new work or a new price.
- Put permits in the contract. In Ontario the homeowner is responsible for permits unless the contract says the contractor will get them.
- Pay against progress, not the calendar: framing inspected, drywall up, final inspection passed.
- Check that electrical work is done by an ESA Licensed Electrical Contractor and plumbing by a licensed 306A plumber, and ask whether the quote includes tax.
Questions people ask
Sources
- City of Toronto — Building permit fees (2026) · toronto.ca
- City of Toronto — Secondary suites permit guide · toronto.ca
- Town of Newmarket — Schedule I, building permit fees 2026 · newmarket.ca
- Town of Newmarket — Additional residential units · newmarket.ca
- Ontario.ca — Your rights when starting home renovations or repairs · ontario.ca