Toronto now lets owners build up to four homes on almost any residential lot without a rezoning, and up to six in parts of the city. That changes the math on an aging detached house, but zoning is only the first gate. The Building Code, water and sewer servicing, construction cost and financing decide whether a multiplex works on a given lot, and this guide walks through each one the way we assess them on a site visit.
Quick answer: As of 2026, the City of Toronto permits multiplexes of two to four units in residential zones city-wide, plus fiveplexes and sixplexes in the Toronto and East York district and Ward 23 (Scarborough North) under By-law 654-2025, enacted June 26, 2025. A new-build multiplex typically costs $350 to $650 per square foot to construct, while converting an existing house usually runs $200 to $450 per square foot for the gut plus $400 to $700 per square foot for any added space, before land, design, soft costs and HST. Toronto's development charges by-law exempts the second, third and fourth units and reduces the charge on a fifth or sixth unit to zero, as long as the lot has no more than six units.
Key takeaways
- Four units city-wide, six in two areas. At least one unit must sit entirely or partially above another. Units built side by side are treated as semis or townhouses under zoning, with different rules.
- Zoning is more generous than for a house. Multiplexes are exempt from "d" floor space index limits, get a 10 metre height maximum where the height overlay shows less, and duplexes to fourplexes have needed no on-site parking since February 3, 2022. Lot coverage and setbacks still apply.
- Watch the fourth unit. Ontario Regulation 462/24 relaxes several zoning standards for up to three units on a lot, but adding a fourth puts the whole lot back under City zoning, and anything permitted only by the regulation can become a deficiency.
- Units two to six generally carry no City development charges or parkland cash-in-lieu. Chapter 415 of the Municipal Code, as amended in 2025 and 2026, covers lots with up to six units; the first unit and any school board charges are assessed separately, so confirm the total before you budget.
- The Building Code drives cost more than finishes do. Fire separations, exits, sound control and, in some designs, sprinklers set the budget, and three or more units moves Toronto Building's review out of the House stream.
- Servicing is a real line item. More units put more fixtures on the water service and sewer, and houses built before the mid-1950s may still have a lead water service.
What Toronto allows in 2026
Toronto's zoning defines a multiplex as a residential building with two, three or four units, with at least one unit entirely or partially above another. City Council adopted city-wide multiplex permissions in May 2023. On June 25 and 26, 2025, Council went further, adopting zoning that permits fiveplexes and sixplexes in the area covered by the Toronto and East York Community Council and in Scarborough North, the area bounded by Steeles Avenue, Neilson Road and the Rouge River, Highway 401 and Midland Avenue. Council also adopted a Multiplex Monitoring Zoning By-law (648-2025) at the same time, so check the current consolidated rules rather than a 2023 summary. Six units across the whole city has been studied under Toronto's federal Housing Accelerator Fund commitments, but as of this writing sixplexes are permitted only in those two areas.
| Building type | Where it's permitted in 2026 | Zoning points that matter |
|---|---|---|
| Duplex, triplex, fourplex | R, RD, RS, RM and RT zones city-wide | One unit above another; 10 m height where the overlay shows less; "d" FSI limits don't apply (a site-specific exception can still set one); lot coverage and setbacks do |
| Fiveplex, sixplex | Toronto and East York district and Ward 23 | Detached buildings only; height can rise to 10.5 m with a partly raised lowest unit; semis and townhouses can't be converted to five or six units |
| Multiplex plus a garden or laneway suite | Lots that also meet the suite rules | An accessory unit can share a multiplex lot if its own regulations are met |
The 10.5 metre allowance for fiveplexes and sixplexes is specific. The bottom of the lowest level's ceiling joists must sit 1.0 to 1.5 metres above established grade across at least 80 per cent of that level, the level needs a floor-to-ceiling height of at least 2.4 metres over 80 per cent of its area, and it must contain a dwelling unit. In plain terms, the by-law rewards a bright, partly raised lower unit over a deep basement.
An existing detached house can be converted to five or six units and keep its status as a lawfully existing building, as long as the new units fit entirely within the building as it existed before the permit. Any addition has to meet zoning or be approved as a minor variance. Multiplexes may also have more than one front entrance and up to two balconies or decks per unit, one at the front and one at the rear, on the second storey or above.
Ontario's three-unit rule and the fourth-unit trap
Ontario Regulation 462/24 came into force on November 20, 2024. It applies when adding a unit results in no more than three units on a lot, such as a house with a basement suite and a garden suite. Where it applies, lot coverage for all buildings can reach 45 per cent unless the City allows more, there is no maximum floor space index, angular planes don't restrict the buildings involved, and the minimum lot area is the same as for a house without the extra unit.
The catch is the fourth unit. Toronto's own guidance gives the example of a duplex with a garden suite built using the regulation's permissions. If the owner later converts the duplex to a triplex, the lot reaches four units, the whole proposal has to meet City zoning, and any feature allowed only by the regulation becomes a deficiency that may need a variance. Our advice is simple: decide the long-term unit count before the first permit, and design to the rules that will govern the finished lot. If a rear suite is part of the plan, our guide to laneway and garden suites in Toronto covers that side of the lot.
Convert the house or build new?
| Factor | Convert the existing house | Build a new multiplex |
|---|---|---|
| Structure and foundation | Works when both are sound and the basement can be made into a legal unit | Designed for the unit count from the footings up |
| Zoning position | Keeps lawfully existing status for parts of the house that exceed today's rules | Must meet current zoning or win variances |
| Unit layout | Constrained by existing stairs, walls and window positions | Kitchens and bathrooms stack, shafts line up, each unit gets a clean exit |
| Typical construction cost | $200 to $450 per sq ft to gut, plus $400 to $700 per sq ft for added space | $350 to $650 per sq ft |
| Time on site (our typical planning range) | Often 6 to 10 months for a gut with an addition | Typically 8 to 14 months |
Conversion makes sense when the house is structurally sound, the basement has usable height or can be lowered economically, and every unit can get its own exit without carving the house apart. When the basement needs lowering, underpinning adds roughly $70 to $150 per square foot, or about $35,000 to $85,000 on a typical footprint, which is why basement height is the first thing we measure. Our comparison of underpinning and benching explains the two methods, and our guide to legal basement apartments in Toronto covers that unit in detail.
A new building lets you stack the units so plumbing walls line up, run fire-rated shafts for pipes and ducts, and design a raised lower unit that qualifies for the extra height where the sixplex rules apply. It also costs more and starts with a demolition. Our guide to renovating versus rebuilding in Toronto works through that decision in more depth.
Building Code: where multiplex budgets are won or lost
The 2024 Ontario Building Code took effect on January 1, 2025, and since April 1, 2025 every permit application must use it. It adopts the National Building Code of Canada 2020 with Ontario amendments.
For two units, the province's homeowner guide to adding a second unit in a house more than five years old describes a 30-minute fire separation between the units and between units and common areas, which can be reduced to 15 minutes when the whole house has interconnected smoke alarms. The same guide notes that lath-and-plaster construction typically provides about a 15-minute separation, and that a basement second unit can have a ceiling height of 1.95 metres over its required floor area. The province flags that parts of the guide are being updated, so we confirm each item against the current Code on every project.
Once a building has three or more units, the requirements step up. Expect fire-rated separations around every unit and any shared stair or corridor, fire-stopping wherever a pipe, duct or wire passes through those separations, sound-rated assemblies between units, and exits that work for each unit without passing through another one. Depending on the building's height, floor area, unit count and how firefighters reach the entrances from the street, the design may need sprinklers. Larger buildings move from Part 9 of the Code into Part 3, which changes both the design team and the City's review. None of this can be relaxed at the Committee of Adjustment, which varies zoning rules, not the Building Code.
The unit count also changes how Toronto Building reviews the file:
- House stream: detached, semi-detached or row houses with no more than two units. Complete applications are reviewed within 10 business days.
- Small Building stream: Part 9 buildings that aren't houses, which is where a triplex or fourplex within Part 9 typically lands. Complete applications are reviewed within 15 business days.
- Large and Complex stream: Part 3 buildings, reviewed within 20 business days for large buildings and 30 for complex ones.
In each stream, an application only counts as complete when it includes an issued Zoning Applicable Law Certificate. On site, Toronto inspects fire separations and fire-stopping before interior finishes go on, and life safety systems such as sprinklers and fire alarms at completion.
Servicing: water, sewers and power
Servicing rarely shows up in early multiplex budgets, and it should.
- Water service. Toronto notes that houses built before the mid-1950s may have a lead water service pipe, and Toronto Public Health recommends replacing the private side at the same time the City replaces its portion. Four kitchens and several bathrooms also demand more of the service than one house did, so we size the incoming line early with the plumbing designer.
- Sewer and drains. We camera the existing lateral before pricing. Toronto inspects the water service and outside storm and sanitary sewers at completion, before backfilling. The City's Basement Flooding Protection Subsidy is open to owners of single-family homes through fourplexes; for work completed on or after November 12, 2025 (with applications under the new amounts accepted from May 1, 2026), it offers up to $6,650 per property, including up to $1,600 per backwater valve for a maximum of two.
- Road and boulevard work. Projects with exterior work pay a Municipal Road Damage Deposit as a partial guarantee against damage to the curb, sidewalk, road and boulevard.
- Electrical and heating. Multiplexes often need a larger electrical service and, depending on the design and the utility, separate metering for each unit, and separate heating and cooling systems per unit keep shared ducts from crossing fire separations. We start the utility conversation early because it runs on its own timeline.
Parking, trees and the rest of the lot
- Parking. As of February 3, 2022, duplexes, triplexes and fourplexes don't have to provide parking. If you do provide it, it must meet the zoning standards.
- Trees. Toronto's Tree Protection By-law covers private trees 30 centimetres or more in diameter and street trees of any size. Since September 1, 2026, a new Distinctive Tree category gives extra protection to healthy trees more than 61 centimetres in diameter, and Council has endorsed lowering the private-tree threshold to 20 centimetres, pending a 2027 report. A rear addition or larger footprint often runs into a protected tree's root zone.
- Ravines and floodplains. Under Ontario Regulation 41/24, development activity in a conservation authority's regulated area includes changes that increase the number of dwelling units. TRCA says its permit is required before the City issues a building permit.
- Tenants. If an existing tenant has to move out for the work under an N13 notice, Toronto's Rental Renovation Licence By-law requires the landlord to apply for a licence within seven days of issuing the notice, with rent-gap payments and a moving allowance of $1,500 or $2,500 depending on unit size. Building permit applications include a screening form for this.
The approvals sequence
- Zoning review. A Zoning Applicable Law Certificate confirms what complies and lists any variances.
- Committee of Adjustment, if needed. For 2026, minor variance fees are $2,228.98 for additions and alterations to existing dwellings with three units or less, $5,011.08 for other residential dwellings with three units or less, and $6,485.59 for all other residential applications. Multiplex variances commonly involve setbacks, building depth and lot coverage, and our Committee of Adjustment guide covers how those hearings run.
- Building permit. Toronto's Multiplex Conversion guide covers converting a house into anything from a duplex to a sixplex. As of January 1, 2026, permit fees include $56.33 for each new residential unit on top of the per-square-metre rates.
- Construction and inspections, from footings through fire separations to final.
- Occupancy and final inspections for every unit before tenants move in.
What it costs: two worked examples
A new 4,200 sq ft fourplex. At $350 to $650 per square foot, construction runs about $1.47 million to $2.73 million. Design and drawings typically add 8 to 15 per cent of the construction budget, or roughly $118,000 to $410,000. Demolition, servicing, permits, financing costs and HST come on top, and land is separate.
Converting an 1,800 sq ft house into a fourplex. Assume a gut and reconfiguration of the 1,800 square feet above grade, a 600 square foot rear addition and a legal basement unit:
| Line item | Typical 2026 range |
|---|---|
| Gut and reconfigure 1,800 sq ft at $200 to $450 per sq ft | $360,000 to $810,000 |
| Rear addition, 600 sq ft at $400 to $700 per sq ft | $240,000 to $420,000 |
| Basement unit where ceiling height already works | $50,000 to $80,000 |
| Underpinning if the basement must be lowered | add $35,000 to $85,000 |
| Construction subtotal before design, permits, servicing and HST | about $650,000 to $1.4 million |
Finish level, the condition of the existing house and how much the Building Code asks for in fire and sound separation decide where a project falls in that range.
Does it pay? An illustrative calculation
Whether a multiplex pays depends on your rents, financing, taxes and how long you hold the property. Treat the table below strictly as a template: the rents are placeholders chosen for the arithmetic, not market data, and this is not financial advice. Replace every number with your own and review them with your accountant and lender.
| Line | Scenario A | Scenario B |
|---|---|---|
| Project cost for three added units | $900,000 | $900,000 |
| Assumed rent per added unit, per month | $2,300 | $2,800 |
| Gross annual rent, three units | $82,800 | $100,800 |
| Assumed 30 per cent for vacancy, maintenance, insurance, utilities and added property tax | $24,840 | $30,240 |
| Net annual income before financing and income tax | $57,960 | $70,560 |
| Simple return on project cost | 6.4 per cent | 7.8 per cent |
If you borrow at a rate close to that return, the project pays mostly through the value it adds to the property and long-term rent growth rather than monthly cash flow. A few things change the picture quickly. Construction loans usually advance in draws tied to progress, so a delayed schedule means paying interest longer. Lenders can treat a small multiplex differently from a larger rental building, so ask yours early how it would underwrite a fiveplex or sixplex. Tax treatment of new rental housing, including HST, can be complicated, so get accounting advice before you sign a construction contract. Our Buildertrend schedules, photos and change-order records give lenders and accountants the documentation they ask for.
What we check on a multiplex site visit
- Zone, overlays, lot coverage and whether the lot sits in the sixplex areas
- Basement height, foundation condition and the cost of lowering
- A workable exit route for every unit
- Water service size and material, and a camera inspection of the sewer lateral
- Electrical service capacity and room for separate meters
- Protected trees on the lot and on the boulevard
- Ravine or floodplain mapping
- Existing tenants and their rights
For the build itself, our custom home team in Toronto handles new multiplexes, our home additions in Toronto cover rear and upper-storey space for conversions, and our basement finishing work in Toronto covers the lower unit. Owners who want design and construction under one contract often choose design-build.
FAQ
How many units can I build on my Toronto lot in 2026?
Up to four in a multiplex in residential zones city-wide, and up to six in a detached building in the Toronto and East York district and Ward 23. A garden or laneway suite can sometimes be added as well if the lot meets those rules. Lot coverage, setbacks, height and the Building Code decide what actually fits.
Do I need a Committee of Adjustment approval for a fourplex?
Not if the design meets zoning, because multiplexes are permitted as-of-right. Many projects still need a variance for something specific, such as a setback or lot coverage, and a zoning review before design is finalized tells you early.
Do multiplexes pay development charges in Toronto?
Mostly not. Under section 415-6 of Toronto's Municipal Code, as amended by By-law 650-2025 in June 2025, development charges aren't imposed on the second, third or fourth unit, and on a fifth or sixth unit they're reduced to zero, provided no more than six units are built on the parcel. Section 415-30 exempts the second through sixth units from parkland cash-in-lieu on the same six-unit basis. The first unit is treated separately, and education development charges are a separate line, so confirm the full figure with the City for your project.
Does a multiplex need sprinklers?
It depends on the design. A duplex usually doesn't. As the unit count, height and floor area grow, or when firefighter access from the street is limited, the Building Code can call for sprinklers or a Part 3 design. Your designer should answer this before you commit to a layout.
Is it cheaper to convert my house or build new?
Conversion is usually cheaper per square foot when the structure is sound and the basement works. New construction typically costs $350 to $650 per square foot but gives you stacked plumbing, cleaner fire separations and better unit layouts. When a conversion needs underpinning, a large addition and major structural changes, the gap narrows.
How long does a Toronto multiplex take?
In our typical planning, design and permits take 2 to 6 months, longer if a variance is needed. On site, conversions with an addition often take 6 to 10 months and new builds typically take 8 to 14 months, confirmed once the design is set.
Thinking about a multiplex? We'll walk the lot, test the zoning and Code questions that decide feasibility, and price the build as a fixed-price contract. Learn more about our custom home building services, start with a free online estimate, or contact us to book a site visit.