How to screen a Toronto house lot before you buy: a builder's due diligence list

Key takeaways

• Start with the zone label, the u number and any Chapter 900 exception on the City's interactive zoning map.
• Measure frontage and depth against the 36.0 and 40.0 metre tests before you count floor area.
• Since September 1, 2026, a private tree is protected if one stem is 30 centimetres or more across, and street trees at any size.
• A lot inside the ravine protection area protects every tree, and a lot near a watercourse gets TRCA review.
• Garden suite firefighter access comes from the Building Code and cannot be varied by the Committee of Adjustment.
• Tenants need at least 120 days' notice for a demolition, plus one month's rent in a building of fewer than five units.

Why screen a lot before the offer

A house lot that looks right from the street can lose a unit, a storey or a whole garden suite to a rule you only find after the purchase. Most of those rules are public. The City's maps and pages answer them, and the answers change what a builder can pay. This guide is the list I work through on a Toronto house lot before a builder makes an offer. It covers the zoning map first, then the lot's shape, then the things on and around the lot that can change a plan: trees, ravines, heritage, emergency access and tenants.

The rules for how many units the zoning allows are in the multiplex zoning guide, and the costs are in the development charges guide. The developer hub shows where this screening sits in the full process.

What is the first check on a Toronto lot?

Open the City's interactive zoning map and search the address. The City's Considerations When Building Multiplexes page says the search returns a box of key zoning information, with links to the by-law chapter, the by-law section and any Chapter 900 exception for the property. Write down four things.

• The zone, such as RD, RS, RT or RM. It decides which building types are allowed and which clause numbers hold the height and setback rules.
• The "u" number, if there is one. It is the most units the lot may hold.
• A "d" number, which is a floor space index limit. The Considerations page says it does not apply to multiplexes.
• An "(x)" with a number, which points to a Chapter 900 exception. Open it and read it in full. An exception can carry its own floor space index that still applies to a multiplex, and its own lot and building rules.

Then turn on the overlays. The Considerations page tells you to open the Legend tab and tick Height, then Lot Coverage, under Overlay Layers. If the Height Overlay shows less than 10 metres, a multiplex may still reach 10 metres. If the lot has a coverage figure, that limit still applies to a multiplex.

How do frontage and depth decide what fits?

Frontage is the width of the lot at the street, and depth is the distance from the front lot line to the rear. Both come from a survey. A listing or an old plan can be wrong, so ask for the survey early.

Depth matters most for a multiplex. By-law 648-2025 allows a 19.0 metre deep building only where the lot is at least 36.0 metres deep and less than 10.0 metres wide, or at least 40.0 metres deep and 10.0 metres wide or more. A lot that misses both tests keeps the zone's normal building depth, which is 17.0 metres in the R zone. Two extra metres of depth across a narrow building add floor area on every level.

Frontage sets how much width the side yards leave. Multiplexes follow the same setbacks as other residential buildings in the zone, held in clause 10.##.40.70 for each zone. On a Major Street, frontage also sets the number of townhouse units, as the Major Streets guide explains. If the lot is wide enough to split, the severance and minor variance guide covers what a split involves.

Is the lot in a sixplex area, on a Major Street, or next to a lane?

Three location checks change the count. A lot in the Toronto and East York district or the Ward 23 area can hold five or six units in a detached building. A lot that abuts a street on Map 3 of the Official Plan falls under the Major Streets rules. A lot that shares a property line with a public lane can take a laneway suite, under rules the City has applied across Toronto since July 16, 2019. Each of these has its own guide: multiplex zoning, Major Streets and laneway suites.

Which trees are protected?

The City's tree by-laws changed on September 1, 2026, and the City says the changes bring stronger protection for existing trees. Under Municipal Code Chapter 813, as amended by By-law 402-2026 from that date, a tree on private property is protected if at least one stem measures 30 centimetres or more in diameter. A tree planted as a condition of a variance, a consent, a site plan or a permit is protected at any size. Every tree on a City street is protected at any size, and street trees can stand in the part of a front yard next to the road.

The City's tree permit page explains how to measure. Mark the trunk 1.4 metres above the ground, wrap a tape around it at a right angle to the trunk, and divide the circumference in centimetres by 3.14. A result of 30 or more means the tree is protected. For a tree with several stems, the largest stem decides. Damage to roots counts as injury, so excavation, a new driveway or stored material inside a tree's protection zone can need a permit even if the tree stays.

Neighbours' trees count too. A Committee of Adjustment application must include photos of every by-law protected tree on the site and within 6 metres of it, or within 12 metres in a ravine protection area, and a site plan that shows each one with its species, diameter and protection zone. A large tree just over the side lot line can fix where your foundation goes.

Ravines, creeks and the TRCA

Open the City's Ravine and Natural Feature Protection By-law map, search the address and turn on that boundary. If the lot sits in the striped area, every tree on it is protected regardless of size. Changing the slope, placing fill, and building or replacing structures or retaining walls all need a permit.

A lot near a watercourse brings in the Toronto and Region Conservation Authority. The City's Committee of Adjustment process page says applications for such lots are sent to the TRCA for input or approval, and that the TRCA charges for the service. Add that review to the timeline.

Heritage and archaeology

A property on the City's Inventory of Heritage Properties, listed or designated, may need a Heritage Impact Statement with a Committee of Adjustment application. Land on the City's database of archaeological potential may need an archaeological assessment. Both requirements are on the City's Committee of Adjustment process page. In the Teiaiagon-Baby Point Heritage Conservation District, adopted by Council on December 18, 2024, the City's tree page says a heritage permit may be needed in addition to a tree permit.

Can the lot take a garden suite?

The City's Garden Suites page, updated August 21, 2026, says a garden suite has to meet firefighter and emergency access rules. Those rules sit in the Ontario Building Code, are checked by Toronto Building and Toronto Fire Services, and cannot be varied by a minor variance. A lot with a narrow side yard and no lane may fail that test even when the zoning allows the suite. Read the garden suites page before you count a suite in the yield.

What if the house has tenants?

Ontario's Residential Tenancies Act sets the terms. A landlord who needs a unit back to demolish it must give notice of at least 120 days, ending on the last day of a rental period or a fixed term, under subsection 50(2). Under section 52, the landlord must pay the tenant one month's rent, or offer another unit the tenant accepts, where the building has fewer than five units, and three months' rent where it has five or more. Whether the seller delivers the house empty or you take on the tenancies is a point for your lawyer and the purchase agreement.

Toronto adds its own rules. The City's Rental Renovation Licence covers renovations that need the tenant to move out. The City's page for landlords says enforcement began on July 31, 2025, the application is due within seven days of an N13 notice, and the fee is $728 per unit. Demolition of rental housing follows the City's separate rental demolition and replacement process under Municipal Code Chapter 667. In a rental building of six or more units, changing the number of units or bedrooms can count as demolition under that chapter.

Ask the City in writing

Toronto Building answers zoning questions for a specific property at 416-397-5330, from 8:30 a.m. to 4:30 p.m., Monday to Friday. For a written answer on a design, apply for a Zoning Applicable Law Certificate. Toronto Building's 2026 fees are $644.38 for a new house, an addition or a conversion, $888.14 for another new building of 300 square metres or less, and $1,863.82 for a larger one. A Zoning Use Review, which confirms whether a use is permitted at a location, costs $214.79.

A screening sheet

How I screen a lot for a builder

I start at the zoning map, write down the label, then read any exception. I check the survey for frontage and depth, mark the sixplex boundary and Map 3, and walk the lot and the lots beside it for trees, slopes and access. I ask the seller about tenants and about any past Committee of Adjustment decisions. Only after that do I test the numbers with the builder, using the feasibility guide. Development potential is specific to each property, so confirm what the zoning allows on a site with the City of Toronto before you commit.

Questions to ask before you buy

• What does the zone label say, and have you read the Chapter 900 exception in full?
• Does a current survey show the frontage and depth you are counting on?
• Which trees on the lot, on the street and next door are protected, and where are their protection zones?
• Is the lot in a ravine protection area or near a watercourse?
• Is the property on the heritage inventory or in an area of archaeological potential?
• Can a firefighter reach the back of the lot if you plan a garden suite?
• Who lives in the house now, and on what terms?

Owners who want to know what a builder looks for can read the For Sellers page. My post on Toronto's low-rise neighbourhoods describes the areas where these lots sit. What on this lot could change the plan, and have you checked it before you sign?

Frequently asked questions

What is the first check on a Toronto lot before a builder makes an offer?

The first check on a Toronto lot before an offer is the zone label on the City's interactive zoning map, which shows the zone, any u number and any Chapter 900 exception. The City's Considerations When Building Multiplexes page says the map's search box returns key zoning information for a property, with links to the exception text and the by-law sections that apply.

How do frontage and depth change what fits on a Toronto lot?

Frontage and depth decide whether a Toronto lot qualifies for the longer multiplex building. By-law 648-2025 allows a 19.0 metre deep houseplex only on a lot at least 36.0 metres deep and under 10.0 metres wide, or at least 40.0 metres deep and 10.0 metres wide or more. Frontage also sets how much width is left after the side yards.

Which trees are protected on a Toronto building lot?

On a Toronto building lot, a private tree is protected if at least one stem measures 30 centimetres or more in diameter, under Municipal Code Chapter 813 as amended by By-law 402-2026 from September 1, 2026. Trees planted as a condition of a variance, consent or site plan are protected at any size, and every tree on a City street is protected regardless of size.

How do you measure whether a tree is protected in Toronto?

To measure whether a tree is protected in Toronto, wrap a tape around the trunk 1.4 metres above the ground, divide the circumference in centimetres by 3.14, and check whether the result is 30 or more. The City's When to Apply for a Tree Permit page gives that method, and for a tree with several stems the largest stem decides whether the whole tree is protected.

How does a builder find out if a Toronto lot is in a ravine protection area?

A builder finds out if a Toronto lot is in a ravine protection area by opening the City's Ravine and Natural Feature Protection By-law map, searching the address and turning on that boundary layer. If the lot sits in the striped area, every tree on it is protected regardless of size, and changing slopes, placing fill or building new structures needs a permit.

What notice must a landlord give tenants before demolishing a house in Ontario?

A landlord in Ontario must give tenants at least 120 days' notice to end a tenancy for demolition, under subsection 50(2) of the Residential Tenancies Act, and the date must fall at the end of a rental period or fixed term. In a building with fewer than five units, subsection 52(2) also requires one month's rent or another unit the tenant accepts.

Does Toronto's Rental Renovation Licence apply to a builder?

Toronto's Rental Renovation Licence applies to a builder who owns tenanted units and gives an N13 notice for renovations that need the tenant to move out. The City's page for landlords says enforcement began on July 31, 2025, the application is due within seven days of the N13 notice, and the fee is $728 per unit. Demolition follows the City's separate rental demolition process.

What does a Zoning Applicable Law Certificate cost in Toronto?

A Zoning Applicable Law Certificate in Toronto costs $644.38 for a new house, an addition or a conversion, $888.14 for another new building of 300 square metres or less, and $1,863.82 for a larger one, under Toronto Building fees effective January 1, 2026. A new garden or laneway suite review costs $644.38, and a Zoning Use Review costs $214.79.

Can every Toronto lot take a garden suite?

Some Toronto lots cannot take a garden suite because the suite needs a route for firefighters and emergency crews. The City's Garden Suites page, updated August 21, 2026, says those access rules come from the Ontario Building Code, are checked by Toronto Building and Toronto Fire Services, and cannot be varied by a minor variance from the Committee of Adjustment.

Does a heritage listing affect a Toronto infill lot?

A heritage listing can affect a Toronto infill lot, because a Committee of Adjustment application for a property on the City's Inventory of Heritage Properties may need a Heritage Impact Statement. The City's Committee of Adjustment process page lists that requirement, along with an archaeological assessment where the land is on the City's database of archaeological potential. Check both before you design.

When does the TRCA review a Toronto infill application?

The Toronto and Region Conservation Authority reviews a Toronto infill application when the property is close to a watercourse, according to the City's Committee of Adjustment process page. The City sends the application to the TRCA for its input or approval, and the TRCA charges for that service. A builder should find out early whether a lot sits near a creek or a ravine slope.

How does a builder read the Height and Lot Coverage overlays for a Toronto lot?

A builder reads the Height and Lot Coverage overlays on the City's interactive zoning map by opening the Legend tab and ticking Height or Lot Coverage under Overlay Layers, according to the City's Considerations When Building Multiplexes page. If the Height Overlay shows less than 10 metres, a multiplex may still reach 10 metres, and a lot coverage figure still applies to it.

Sources

1. Considerations When Building Multiplexes. City of Toronto. Updated June 30, 2025. Accessed November 1, 2026.
2. By-law 648-2025, detached and semi-detached houseplexes. City of Toronto. Enacted June 26, 2025. Accessed November 1, 2026.
3. Toronto Municipal Code Chapter 813, Trees. City of Toronto. Consolidated to September 1, 2026. Accessed November 1, 2026.
4. When to Apply for a Tree or Ravine Permit. City of Toronto. Updated January 29, 2026. Accessed November 1, 2026.
5. Tree and Ravine Protection Permits. City of Toronto. Updated October 13, 2026. Accessed November 1, 2026.
6. Garden Suites. City of Toronto. Updated August 21, 2026. Accessed November 1, 2026.
7. Changing Lanes: Laneway Suites in Toronto. City of Toronto. Updated February 29, 2024. Accessed November 1, 2026.
8. About the Committee of Adjustment and Rules of Procedure. City of Toronto. Updated October 2, 2026. Accessed November 1, 2026.
9. Committee of Adjustment Forms, Submission Guidelines and Fees. City of Toronto. Updated October 8, 2026. Accessed November 1, 2026.
10. Residential Tenancies Act, 2006, S.O. 2006, c. 17. Government of Ontario, e-Laws. Current version from September 21, 2026. Accessed November 1, 2026.
11. Rental Renovation Licence: Information for Landlords. City of Toronto. Updated July 9, 2026. Accessed November 1, 2026.
12. Building Permit Fees. City of Toronto, Toronto Building. Updated June 19, 2026. Accessed November 1, 2026.

Planning and development potential is property-specific and subject to zoning, approvals, site conditions, municipal review and other due diligence. This guide gives general information. For legal, tax or financial advice, ask your own lawyer and accountant.