How Much Does It Cost to Build a Basement or Backyard Rental Suite in Toronto? (Costs, Permits, Payback)

A legal basement rental suite in Toronto usually costs between $50,000 and $110,000 all in. A garden suite in the backyard runs higher, often past $100,000, because you're building a small house from scratch.

Here's where that money actually goes, based on the pricing we quote every week.

What a basement suite costs

The big three line items:

• Kitchen: $25,000 to $65,000. A simple galley kitchen sits at the low end. Full custom cabinets push it up fast.
• Bathroom: $12,000 to $28,000, depending on fixtures and how much the plumbing moves.
• Waterproofing, if the basement is damp: $4,000 to $12,000. Do this first. Nobody rents a unit that smells like a wet basement.

Those three lines already add up to $41,000 to $105,000. Then you add framing, flooring, electrical upgrades, egress windows, and permit fees. That's how most finished suites land between $50,000 and $110,000. Also worth doing while you're at it: eavestrough replacement runs $2,000 to $4,800, and downspouts that carry water away from the foundation are cheap insurance for a dry unit. A dry basement starts at the eaves, not inside it.

What a backyard (garden) suite costs

Same kitchen and bathroom money, $37,000 to $93,000 for those two rooms. Then add a foundation, framing, roofing at $5,500 to $12,000, and siding at $3,000 to $9,000, plus real servicing: sewer, water, and hydro connections. The total almost always beats the basement route, even when the suite is smaller. The payoff is you keep your basement.

Permits: what the city actually asks for

Basement second suites are legal in most detached and semi-detached homes in Toronto. The city will want:

• A building permit. Skipping it risks fines, insurance problems, and an order to rip the unit out when you sell.
• An egress window in every bedroom, sized to code.
• Minimum ceiling height, about 1.95 metres in most existing basements. Under that, the project stalls before it starts.
• Fire separation between the units, interconnected smoke and CO alarms, and a separate entrance for tenants.
• Electrical and plumbing permits with inspections along the way.

Garden suites have been legal across Toronto since 2022. You'll deal with zoning rules on height, lot coverage, and setbacks from your property lines. Some lots comply as-is. Some need a minor variance at the Committee of Adjustment, which means neighbours get a say. Parking is where more of these projects die than anywhere else, so figure out tenant parking before you file anything.

Why fall is the right time to start

Second suite permits often take weeks to a couple of months. Garden suites take longer, especially with a variance. File now, get approvals through winter, build in spring, and collect rent by summer. If your basement is damp, waterproof before the ground freezes. It's $4,000 to $12,000 now instead of a rip-and-redo after the drywall is up.

The payback math, and the honest catches

A decent legal one-bedroom basement apartment in most Toronto neighbourhoods has been renting between roughly $1,700 and $2,400 a month lately. Garden suites often rent higher. At $2,000 a month, a $60,000 basement build pays for itself in about two and a half years of rent. Call it three to five once you count vacancies.

Now the catches, because there are always catches:

• You lose your storage. The suite eats the rec room, the exercise space, and half the laundry setup.
• You're a landlord now. Vacancies, late-night calls, and repairs come with the rent cheques.
• Garden suites cost you yard space or a parking spot, and neighbours can slow things down.
• Insurance and property taxes rise a little. Not enough to kill the math, but not zero.

We've been renovating Toronto homes as a family crew since 1979, and the people who do this well treat a suite like a small construction project, not a weekend reno. Want a free ballpark for your house before you commit? Try our cost calculator at lfbuilders.ca/costs/calculator