If you’re planning a garden or laneway suite, a mature tree at the back of your lot can stop it. Urban Forestry can refuse a tree permit for a healthy tree, and the suite then has to fit around the tree. Bring an arborist in before you commit the footprint.
Not Every Backyard Tree Is Protected
A private tree is protected under Chapter 813 of Toronto’s Municipal Code when its trunk is 30 cm or more in diameter, measured at 1.4 metres above ground. That’s roughly the size of a mature backyard maple that’s been growing for 20 years. If no tree near your build site is close to that size, this conflict does not apply.
Two exceptions to that threshold: if your lot falls in a ravine or natural feature protection area, Chapter 658 covers trees of any size. And street trees require a permit regardless of trunk size, no matter where the trunk sits.
The City’s Position on Suites and Healthy Trees
Garden suites became as-of-right (allowed by default, no rezoning or special approval needed) in Toronto under By-laws 100-2022 and 101-2022. Laneway suites were legalized earlier, through Toronto’s 2019 zoning amendments. The city’s stated goal for the suite program includes maintaining permeable space and expanding the tree canopy.
On a lot with mature trees, that goal and the footprint of a new dwelling unit can work directly against each other. The city’s guidance is direct: a garden suite “should not result in the removal of a healthy by-law protected tree.” The same standard applies to laneway suites. If your proposed design requires removing a healthy protected tree, the city can refuse the tree permit under Chapters 658 and 813 of the Municipal Code. Urban Forestry issues a tree permit only after the building permit is approved, and the tree permit lets you injure or remove the tree only once the building or demolition permit is in hand and that work has started. A refused tree permit leaves you with a building design you cannot build.
What “Protected” Covers
The 30 cm trunk threshold is the entry point, but protection extends beyond the trunk. Any construction that affects a tree’s protection zone (TPZ) requires a permit, even if the tree is staying put. The permit to injure covers that scenario. TPZ radius scales with trunk size: 2.4 metres for a tree in the 30 to 40 cm range, 3.0 metres for 41 to 50 cm, and 3.6 metres for 51 to 60 cm. On ravine-regulated lots, those radii double.
If your lot or the adjacent lane falls in a ravine protection zone, check the “Ravine and Natural Feature Protection By-law” layer in the city’s interactive map tool.
Where the Zoning and the Trees Collide
Zoning fixes the box where you can build. The tree bylaw draws a no-disturb ring around each trunk. On a typical Toronto lot with one or two mature trees, those two overlap.
Garden suite geometry, in brief:
- Minimum rear yard setback: 1.5 metres (on a lot deeper than 45 metres, the greater of 1.5 metres or half the suite’s height)
- Minimum separation from the main dwelling: 4.0 metres for a suite up to 4.0 metres tall, 7.5 metres for a taller one
- Maximum floor area: 60 sq m for a one-storey suite, 120 sq m for two storeys
- Lot coverage: 45% for all buildings on the lot, or 20% for all ancillary buildings combined
- Rear yard soft landscaping requirement: at least 50% on a standard lot
The separation, floor area and coverage figures come from Toronto’s 2025 garden suite amendments (By-law 849-2025), which brought the zoning in line with Ontario Regulation 462/24. A suite up to 4.0 metres tall can now sit closer to the house than it could before 2025. On a short lot, that extra metre can be enough to move the footprint out of a tree’s protection zone.
Laneway suites get up to 10.0 metres long and 8.0 metres wide. The rear wall can sit at a 0.0 metre setback when it has no openings and doesn’t abut a street or lane. Trees along the lane side of a rear yard push the footprint further forward and straight into the separation distance from the main house. For laneway suites, combined ancillary lot coverage is capped at 30%.
Emergency access is a constraint that surfaces late in the process. Toronto Building and Toronto Fire review it under the Building Code, so a minor variance cannot relax it. The path from the public street to a garden suite entrance needs 2.1 metres of clear height and a clear width of 1.0 metre (0.9 metres if the suite is sprinklered). A path up to 45 metres long needs nothing more. Between 45 and 90 metres, the City accepts it only with added fire safety measures: a sprinkler system or upgraded fire-rated construction, plus an exterior strobe and an alarm system. A mature low-branching tree along the side passage can fail the clearance test. On a long lot, that can push the project onto the 90 metre route, which needs engineered fire safety systems, or force a design change.
The City’s pre-approved garden and laneway suite plans do not avoid any of this. The building design is pre-reviewed, but its placement on your lot is not, and the Tree Declaration Form is still required wherever private or City trees could be damaged.
An arborist maps this conflict before you commit the footprint. A construction arborist report done at the design stage leaves room to adjust. Done after the drawings are locked, it becomes documentation for a dispute you may not win.
Permit Fees, Replacement and Review Time
- Permit fee: $436.39 per tree for a private tree permit with construction. If the tree is shared with a neighbour, it’s classified as a boundary tree and the construction fee rises to $913.58
- Chapter 813 sets no fixed replacement ratio. Urban Forestry sets the number of replacement trees in the permit conditions, so budget for more than one
- Cash-in-lieu: $583 per required replacement tree, not per tree removed, when on-site planting isn’t feasible. Staff push back on it where they find planting space
See the full replanting breakdown in our post on replanting requirements and cash-in-lieu across the GTA.
Since September 1, 2026, replacement trees planted as a condition of a permit are protected from the day they go in the ground, with no size threshold or waiting period. Full details are in our post on Toronto’s September 2026 tree bylaw amendments.
When the City Approves Removal
A tree that is declining, structurally compromised, or dead is a candidate for removal. A healthy tree in an inconvenient location is a much harder case. Removal because the tree blocks the preferred footprint is a weak basis for a permit application.
Starting September 1, 2026, any tree with a trunk greater than 61 cm in diameter is eligible for Distinctive Tree designation. The city must consider whether any tree in a permit application qualifies, and may refuse a permit to injure or remove a Distinctive Tree. Once designated, the tree’s status is a mandatory review criterion, so plan the suite around a tree that size.
Arborist Reports for Garden and Laneway Suites
Our team prepares construction arborist reports for garden suite and laneway suite applications across Toronto. The report documents every protected tree within and adjacent to the construction envelope, assesses root zone impact, and produces a tree protection plan drawn to the same geometry as your building permit drawings.
If you’re in the design phase, an early site visit shows where the trees limit the footprint before you commit to it. If the drawings are done, we work from the existing design and identify where the conflict points are. Contact us with your address and the current stage of your project and we can confirm the scope before we visit.