Second suite cost calculator.
A rough build range for a basement apartment or a garden suite, from published estimates. It’s a planning number to start your budget with, not a quote.
Start with a rough range. Not a quote.
Estimate: $90 to $150 per sq ft, from a contractor’s published figures.
- 01Larger bedroom window for exits
- 02Full rewire of an older house
- Construction700 sq ft, published estimate.$63,000 to $105,000
- Construction
- Design and drawings
- Permit fees
- HST and financing
A rough planning range, not a quote. Construction figures are published third-party estimates. Your contractor prices the build.
What published estimates say.
These are the ranges behind the calculator. All are third-party estimates, not our prices. Per sq ft and whole-project figures come from different sources, so don’t combine them.
- 01
Basement apartment, per sq ft
Contractor’s blog, 2026.
Published range$90 to $150 per sq ft
- 02
Basement apartment, whole project
Contractor’s published guide.
Published range$80,000 to $130,000
- 03
Garden suite, whole project
Contractor’s published guide.
Published range$175,000 to $300,000 or more
- 04
Larger bedroom window for exits
Contractor’s blog, 2026.
Published range$2,500 to $7,000 per window
- 05
Full rewire of an older house
Contractor’s blog, 2026.
Published range$15,000 to $35,000
- 06
Underpinning for ceiling height
Contractor’s blog, 2026.
Published range$40,000 to $90,000 before finishing
Wide ranges on purpose. The real number depends on the state of your basement or lot, the finishes, and what your municipality requires. Comparing the two types? See Basement Apartment vs. Garden Suite.
What the range leaves out.
Land, HST and financing
The range is the build alone, before tax and the cost of borrowing.
Design and permit drawings
Quoted separately, and fixed once we quote your project.
Municipal fees
The building permit fee, deposits and registration fees. Each municipality sets its own.
Development charges
A 2nd or 3rd unit in a house is exempt under the provincial rule. Education charges may still apply in some places.
Grading, septic and variances
Lot grading plans, septic design and minor variance applications.
Furniture and appliances
Budget for these on top of the build.
Cost questions.
Is this a quote?
No. The range comes from published third-party estimates. Your contractor prices the build.
Why is the range so wide?
Because the published estimates are wide, and so are real projects. A basement that is already dry and tall costs less to convert than one that needs new windows or a lower floor.
Does it include permit fees?
No. Building permit fees are set by each municipality, by floor area or construction value, so they are left out of the range. Your building department confirms the fee when you apply.
What should I do before I budget?
Check your lot first. If the rules don’t allow the unit you have in mind, the budget doesn’t matter yet.
Does my property qualify?Pick the question closest to yours.
We’ll quote the design, before you commit.
Send the address and a few photos. We check what your lot allows and quote the drawings.