Basement costs in the GTA, 2026
GTA renovators price basements by the square foot of finished floor. Each rate below is the median of what several GTA renovation companies publish. The Basic, mid-range and premium are what the calculator shows for each finish level: the lower half, the middle and the upper half of the published range.
| Project | Basic | Mid-range | Premium |
|---|---|---|---|
| Family space: framing, insulation, drywall, flooring, lighting. No bathroom. median of 5 companies | $35 – $45 per sq ft | $40 – $50 per sq ft | $45 – $55 per sq ft |
| Legal basement apartment: kitchen, bathroom, bedroom, fire separation, entrance, permits median of 6 companies | $90 – $115 per sq ft | $102.50 – $127.50 per sq ft | $115 – $140 per sq ft |
For a 1,000 sq ft basement with mid-range finishes, that is about $40,000 – $50,000 for a family space and $102,500 – $127,500 for a legal apartment.
Before HST. Prices checked October 15, 2026.
What adds to the price
- A bathroom adds about $15,000 – $25,000. Much of that is cutting the concrete floor for new drains, so it can cost less if capped pipes (a rough-in) are already there. Plumbing is done by a licensed professional.
- A bedroom needs a window big enough to climb out of. Cutting one into the foundation, with its window well, costs about $2,900 – $6,250.
- A new walk-up entrance, with stairs dug down to a new basement door, adds about $18,000 – $30,000.
- A low ceiling may mean lowering the floor (underpinning). On a typical GTA house that adds about $32,500 – $85,000, with an engineer's design and a permit.
- Permit drawings and the building permit for a family basement come to about $3,000 – $6,500.
- Water comes first. If the basement has had leaks, waterproofing is extra and is done before finishing. GTA renovators advise keeping 10% to 15% of the project aside for problems found once walls are opened.
Making it a legal second unit
Ontario’s guide to adding a second unit sets out the main rules for a basement apartment:
- A ceiling at least 1.95 m (6 ft 4¾ in) high over the required floor area, including the way out.
- A 30-minute fire separation between the two units, and between each unit and any shared space.
- A safe way out for each unit. A shared side door can work if the exit area has a 30-minute fire separation and smoke alarms connected to both units.
Every second unit needs a building permit. In Toronto the 2026 permit fee is $11.53 per square metre of work plus $56.33 for the new unit. Brampton also asks you to register the unit: a $200 registration fee and a $1,186.24 permit fee. Plumbing and electrical work is done by a licensed professional.
How we work out these numbers
We read the prices that GTA renovation companies publish for basement work, keep only 2026 pages from businesses that do the work, and take the middle (median) of their ranges. The rate per square foot is multiplied by your basement’s size range, and your finish level places you in the lower, middle or upper part of it. Every source, with the exact words we quote and the date we read it, is listed under the calculator result.
The calculator gives a budget range, not a quote. Ceiling height, water, the entrance and the finishes you pick change the final price. A free in-home visit gets you a written estimate.