By Sara Rahgozar, M.Arch, OAA, Quadrant Architects
Getting a building permit for a fourplex or any other multiplex in Toronto takes seven steps: check the zoning, confirm the Building Code path, put the team together, prepare the drawings, submit, get through plan review, and pass inspections during construction.
The City approves the permit based on your drawings. How complete and code-compliant they are decides whether it clears on the first review or comes back with deficiency notices (the examiner’s list of required corrections) that add weeks or months.
Key facts
In this guide:
Before your architect starts the full permit drawings, confirm that the proposed design fits every zoning limit in Toronto’s Zoning By-law 569-2013: height, setbacks, lot coverage, building depth, and any site-specific exceptions in Chapter 900. If the design goes over any of these limits, you need a minor variance from the Committee of Adjustment before the City will issue a permit.
Finding a zoning problem after the drawings are done is the most common cause of wasted time and money on Toronto residential projects. For the step-by-step check, see how to check a Toronto property’s zoning. For what fits on a typical lot and when a variance is needed, see building a fourplex in Toronto. For where six units are allowed, see sixplexes in Toronto.
This decides who can prepare your drawings and how much engineering you need. The Ontario Building Code sorts buildings by size and use, not by how many units they have.
| Part 9 | Part 3 | |
|---|---|---|
| Building height | 3 storeys or less | More than 3 storeys |
| Building area (footprint) | 600 m² or less | Over 600 m² |
| Typical example | Most fourplexes and sixplexes on interior lots | A mid-rise apartment building on a major street |
| What it involves | Designed by a BCIN designer or an architect, depending on size (see below) | An architect and professional engineers, with engineered structure, fire and egress design (see our Major Streets guide) |
Often you do, even under Part 9. A BCIN-registered designer (someone holding a Building Code Identification Number from Ontario’s Ministry of Municipal Affairs and Housing) can design many Part 9 buildings. But the Building Code requires an architect for a residential building when:
Gross floor area adds up all the floors above grade. Three floors of just over 200 square metres each puts a stacked three-storey multiplex over 600. Confirm the code path and whether you need an architect before you hire anyone.
For a typical fourplex, you need an architect, a structural engineer, and a land surveyor.
The architect (OAA licensed) prepares the architectural drawings, stamps and seals them, and takes professional responsibility for the design.
The structural engineer (P.Eng.) designs the foundation, framing, and any structural changes. Their drawings have to match the architect’s, and when they don’t, it’s one of the most common reasons examiners send comments back on residential submissions.
The surveyor (OLS licensed) provides the current survey of the property that the permit application requires.
Depending on the project, you may also need a mechanical or electrical engineer, an energy consultant for the Code’s energy requirements, a geotechnical engineer if the soil is a problem, or an arborist if protected trees are affected.
Your architect and engineers put together three things: the architectural drawings (site plan, floor plans, elevations, sections, an egress plan, and a schedule showing the design meets the zoning), the structural drawings stamped by the engineer, and the supporting documents, including the application form, the survey, and energy compliance forms.
Every drawing has to be to scale, fully dimensioned, signed, and dated. What matters most to you as the owner is that the package is complete and that the architectural and structural drawings agree with each other.
You submit it online through Toronto Building Online Services (TBOS). The City has set up self-service submission for multiplex conversions, laneway suites, garden suites, secondary suites, new houses, and new residential units, with automated document checks.
Submit the complete package. An incomplete package gets sent back before a plan examiner ever looks at the design. Missing documents, unsigned forms, or drawings in the wrong format all delay you at this stage.
The City’s target for the first technical review of a residential House Stream application is 10 business days. That covers the first review only, not the whole process.
| Stage | Realistic time |
|---|---|
| Drawing preparation (before you submit) | 4 to 8 weeks, depending on complexity and the architect’s workload |
| First plan review | 10 business days (City target; actual times vary) |
| Revisions and resubmission, if deficiency notices are issued | 2 to 6 weeks per round |
| Submission to permit in hand | 2 to 4 months, longer if revisions are needed |
Every round of revisions adds weeks, which is why the first submission matters so much.
Fire separation. New construction needs a 45-minute fire separation between units. Conversions of existing houses can use a lower rating in some cases, such as 30 minutes for a second unit, or 15 minutes if the whole house has interconnected smoke alarms. Either way, the separation has to be continuous between all units, including between floors.
Egress. Each unit needs at least one means of egress, and exit paths have to meet minimum width and travel-distance requirements.
Light and ventilation. Every habitable room needs a minimum window area and operable ventilation. This matters most for basement units, which have specific requirements for window wells and emergency exit windows.
The Code also sets sound ratings (STC) for the walls, floors, and ceilings between units and minimum sizes for bedrooms, kitchens, bathrooms, and living areas, and it requires interconnected smoke alarms in every unit.
Three things come up at the permit stage that don’t apply to a new build:
For the wider trade-offs between converting a house and building new, see building a fourplex in Toronto.
Before construction starts, you pay the building permit fee, which is based on the project’s construction value, plus fees for the architect, engineers, and survey. Development charges are waived for up to six units under current City policy. Put these costs in the budget from the start.
The City’s target for the first review of a residential House Stream application is 10 business days. Realistically, it takes 2 to 4 months from submission to permit in hand, longer if revisions are needed. Drawing preparation before submission usually takes 4 to 8 weeks.
It depends on size, not the number of units. A residential building of three storeys or less with a building area of 600 square metres or less falls under Part 9, which covers most Toronto fourplexes and sixplexes on interior lots. Larger buildings fall under Part 3.
Often you do, even under Part 9. The Ontario Building Code requires an architect for a residential building that is taller than three storeys, has a gross floor area over 600 square metres with one unit above another, or has a footprint over 600 square metres with three or more units. Three floors of just over 200 square metres each puts a stacked three-storey multiplex over 600 square metres of gross floor area.
Only if the design exceeds a zoning limit under Toronto Zoning By-law 569-2013, such as setbacks, height, lot coverage, or building depth. In that case you need a minor variance from the Committee of Adjustment before a permit can be issued.
Permits get held up by zoning problems found late, the wrong code path, and architectural and structural drawings that don’t match. Quadrant Architects is an OAA-licensed firm in Toronto. Send us the address and what you want to build, and we’ll check the zoning and confirm the code path before any drawings are done.
Call 416-835-0053 or see our residential architecture services. For the full picture on what you can build on a Toronto residential lot, start with our multiplex architect guide for Toronto.
Sara Rahgozar, M.Arch, OAA, Principal, Quadrant Architects
Current as of 2026. Permit processes and fees change, so check current requirements and fee schedules with Toronto Building Customer Service or the City of Toronto website before you apply.