Detached Garden Suites in Toronto, Explained
A detached garden suite is a small, separate home built in the rear yard of a house. The City calls it an additional residential unit (ARU); planners also say detached accessory dwelling unit, and most homeowners just say backyard home. Toronto has allowed them on most residential lots since By-law 574-2022 passed in 2022. They are permitted in the rear yard of detached, semi-detached and townhouse lots, and they must stay on the same title as the main house.
What does a detached garden suite cost in Toronto?
Turnkey detached suites in Toronto run $180,000 to $340,000 with us, and up to $380,000 for complex custom work across the market. A 40 sqm studio sits at the low end. A 60 sqm two-bedroom or a suite with a loft sits at the high end. Soft costs (feasibility, design, permits and engineering) are usually $14,000 to $30,000 of that total. Hard costs cover the foundation, structure, envelope, mechanical, finishes and site work. The line items that move the number most in Toronto are foundation type, utility upgrades on older houses in Riverdale or East York, crane or hand-carry access on narrow lots, and finish level. Development charges are waived for ARUs under provincial Bill 23, which removed a big cost that used to scare owners off.
What are the rules under By-law 574-2022?
By-law 574-2022 sets the maximum size at 60 sqm on most lots, with a 40 sqm cap for narrower lots or small rear yards. It works together with Zoning By-law 569-2013 Chapter 150.7, which sets rear and side setbacks, building separation (generally 5.0 m from the main house, rising to 7.5 m for taller suites), lot coverage and soft landscaping minimums. A firefighter must be able to reach the suite: the path from the street is generally capped at 45 m and needs a clear 1 m width. Lots near a ravine fall under TRCA review, protected trees fall under the Tree Protection By-law, and lots in a Heritage Conservation District go to Heritage Preservation Services.
Who builds detached garden suites in Toronto?
You can hire an architect, a permit expeditor and a general contractor separately, or one design-build firm. We are a Toronto-only design-build practice led by Dmitri Varga, P.Eng since 2003 and BCIN-qualified for Part 9 design. Our team has assessed hundreds of Toronto lots since the by-law passed, and we handle feasibility, design, permits, utilities and construction under one fixed-price contract, so nobody points fingers when a Zoning Examiner sends comments.
What We Do on Every Detached Suite
Our detached suite service breaks into four parts, and you get all four in one contract.
1. Feasibility and envelope study
Before design starts, we visit the lot and produce a written feasibility report. It confirms eligibility under By-law 574-2022, measures the true allowable footprint and height, screens for TRCA, tree and heritage constraints, checks soil and access, and pre-qualifies Toronto Hydro, Toronto Water and Enbridge capacity. It ends with a budget range and a rental estimate. You pay zero deposit for it.
2. Design to the lot, then to your life
Once we know the envelope, we design studio, one-bedroom, two-bedroom or loft layouts in the 40 to 60 sqm range. Drawings include the site plan, floor plans, elevations, sections and SB-12 energy compliance, stamped by our BCIN-qualified team. See our garden suite design service for what the package covers.
3. Permits and utilities in parallel
Our in-house expeditor files the full set with Toronto Building Division, answers every Examiner’s Notice and coordinates Toronto Water, Toronto Hydro and Enbridge while the permit is in review. Our permit application service explains how we hold the 12 to 14 week average.
4. Construction and handover
We build the foundation, frame, close in the envelope, install a cold-climate heat pump, HRV and a 100-amp sub-panel, and finish the interior. Third-party inspectors check foundation, framing, insulation and final. You get a handover binder, the occupancy sign-off and your written warranty.
How Do We Keep a Detached Suite Code-Compliant?
Every detached suite we build is designed and inspected to Ontario Building Code Part 9 for small residential buildings. Part 9 sets the rules for structure, fire separation, egress, insulation and ventilation. We add three checks most builders skip.
Limiting distance and fire protection. If the suite sits close to a side or rear lot line, the wall facing that line may need a fire-resistance rating and limited window area. We design that in from the start instead of discovering it at plan review.
Toronto Green Standard Tier 1. Our standard envelope targets TGS Tier 1: continuous exterior insulation, an airtight layer tested with a blower door, an HRV for fresh air and a cold-climate air-source heat pump that heats down to about minus 25 C.
Fire access. The 45 m travel distance from the street and the 1 m clear path are checked on site, not on a plan. When the path is too long or too narrow, we look at sprinklers or an alternative solution before submission.
The lot coverage trap
By-law 574-2022 caps most suites at 60 sqm, but the cap drops to 40 sqm on narrower lots and shifts with rear yard size. Many homeowners pay for designs drawn to 60 sqm, then learn their lot allows 48. That means a redraw, a resubmission and an 8 to 12 week slip. We measure first.
Which Type of Detached Suite Fits Your Lot?
| Suite type | Typical size | Best for | Price range |
|---|---|---|---|
| Single-storey studio | 40-45 sqm | Narrow lots, home office, small rental | $180K-$240K |
| Single-storey 1-2 bedroom | 46-60 sqm | Rental income, aging parents, step-free living | $230K-$300K |
| Two-storey or loft | 50-60 sqm | Smaller footprint with more living space | $280K-$340K |
| Prefab-hybrid | 40-60 sqm | Faster site schedule, tight budgets | $140K-$240K |
Single-storey suites keep everything on one level and suit multigenerational families who need step-free living. Two-storey and loft suites leave more of the yard open but need more separation from the main house and a height study. If you want a shorter build, a prefab garden suite uses factory-built panels or modules on a site-built foundation.
When Is a Detached Suite the Right Choice?
A detached suite makes sense when your rear yard can fit at least 40 sqm with the required separation, and you want real privacy for a tenant, parent or adult child. It is also the best option for resale value, because it reads as a second home rather than a basement unit.
It may not be the right choice if your lot is very shallow, if a protected tree sits in the middle of the yard, or if you already have a sound detached garage in the right spot. In those cases, an attached garden suite or a garage conversion can deliver more space for less money. If your lot backs onto a public lane, a laneway house may give you a better footprint. The feasibility report tells you which path wins on your lot, in writing.
Detached Suite vs Doing It Piecemeal
Some owners try to save by hiring a drafter, filing the permit themselves and then shopping for a contractor. Here is what that usually costs in time.
| Step | Piecemeal route | One design-build contract |
|---|---|---|
| Lot check | Often skipped | Written feasibility report first |
| Drawings | Drawn to the 60 sqm maximum | Drawn to your measured envelope |
| Permit | 20+ weeks with resubmissions | 12-14 week average |
| Utilities | Started after permit | Pre-qualified in feasibility |
| Price | Grows through change orders | Fixed, with written approvals only |
If you want to see the full budget picture first, our garden suite cost estimation page breaks down hard and soft costs, and our pricing page lists every service range in one table.
