Garden Suite & ADU Regulations in Ontario: What You Need to Know (2026 Guide)
If you’re thinking about building a garden suite, laneway house, or accessory dwelling unit (ADU) on your property in Ontario, the good news is that provincial legislation has made it easier than ever. But “easier” doesn’t mean “simple” — there are still zoning bylaws, building permits, size restrictions, and code requirements you need to navigate before breaking ground. Here’s what Ontario homeowners need to know in 2026.
Under Ontario’s More Homes Built Faster Act (Bill 23), most residential properties connected to municipal water and sewage are now permitted to have up to three residential units — typically the main house, an interior secondary suite (like a basement apartment), and a detached accessory dwelling unit (garden suite or laneway house). This “as-of-right” zoning means you don’t need a costly and uncertain rezoning application to build one. You do, however, need a building permit, and your project must comply with local setback, size, and height requirements.
If you’re wondering what a garden suite costs to build, our Garden Suite & ADU Cost in Ontario (2026 Guide) has the full pricing breakdown by size and type.
What Bill 23 Changed for Ontario Homeowners
Before Bill 23 passed in late 2022, building a garden suite or ADU in most Ontario municipalities required a zoning bylaw amendment — a process that could take 6 to 12 months, cost thousands in planning fees, and had no guaranteed outcome. Bill 23 changed that by requiring municipalities to allow up to three units on most residential lots as-of-right.
Here’s what that means in practice for homeowners in Toronto and across the GTA:
No rezoning required. If your property is in a residential zone (R1, R2, R3, or equivalent) and connected to municipal services, you have the right to build a garden suite without applying for a zoning change. This eliminates the biggest cost, risk, and delay from the process.
No additional parking required. Municipalities can no longer require you to add new parking spaces for an ADU. This is a major change — parking requirements were previously one of the biggest barriers to building garden suites on smaller urban lots.
Development charge exemptions. Ontario Regulation 332/12 exempts garden suites under 100 square metres from development charges. Depending on the municipality, this saves homeowners $20,000 to $40,000 in fees — a significant reduction in overall project cost.
Municipal restrictions limited. While municipalities can still set rules around setbacks, height, and lot coverage, they cannot effectively ban garden suites through overly restrictive bylaws. The province has set the floor — cities can add reasonable conditions, but they can’t say no outright.
Zoning Rules by GTA Municipality
While Bill 23 set the provincial framework, each municipality has its own specific bylaws governing garden suite size, height, setbacks, and lot requirements. Here are the key rules for the most common GTA municipalities:
City of Toronto
Toronto’s Garden Suites Bylaw permits detached ADUs in most residential zones. The maximum footprint is generally the lesser of 10% of the lot area or 60 square metres (approximately 645 square feet), though larger lots may allow up to 90 square metres. Maximum height is 6 metres (about 20 feet), and the suite must be setback at least 1.5 metres from the rear lot line and 1.5 metres from side lot lines. The minimum lot frontage is typically 6 metres, and the lot must be connected to municipal water and sewer.
Markham
The City of Markham permits garden suites on residential lots with a minimum lot area of 450 square metres and minimum frontage of 15 metres. The maximum building size is 90 square metres (approximately 969 square feet) with a 6-metre height limit. Setback requirements typically mirror the main dwelling’s rear and side yard setbacks. Markham’s permitting process has been relatively streamlined for as-of-right projects.
Vaughan
Vaughan permits additional residential units including detached garden suites on qualifying lots. Size and setback requirements are similar to other York Region municipalities — maximum building area around 80 to 90 square metres with a 6-metre height restriction. Lot coverage limits apply and include both the main dwelling and the garden suite.
Richmond Hill
Richmond Hill’s bylaws allow garden suites on eligible residential properties. The maximum permitted size, setback requirements, and height limits are generally consistent with the York Region approach. Homeowners should confirm their specific lot’s eligibility through the City’s planning department or a qualified designer.
Building Permit Requirements
Even though rezoning isn’t needed, a building permit is mandatory for every garden suite project in Ontario. No exceptions. The building permit ensures your suite meets the Ontario Building Code for structural integrity, fire safety, energy efficiency, and habitability.
Here’s what the permit process involves:
Architectural drawings. Your permit application requires detailed drawings — site plan, floor plan, elevations, cross-sections, and foundation details — all drawn to scale. In most municipalities, these must be prepared by a BCIN-registered designer (Building Code Identification Number), a licensed architect, or a professional engineer.
Structural engineering. If the garden suite has a basement or second storey, or if the design includes any non-standard structural elements, a structural engineer’s stamp is required on the drawings.
Application submission. In Toronto, all applications go through the ePlans digital portal. Other GTA municipalities have their own submission processes — some digital, some still paper-based. Ensure your application package is complete before submitting; incomplete applications get sent back and restart the clock.
Permit fees. Building permit fees for garden suites range from approximately $10,500 to $20,000 depending on the municipality and the size of the project. Some municipalities charge additional fees for plan review, inspections, or lot grading review.
Approval timeline. Complete applications that meet all zoning requirements are typically approved in 8 to 16 weeks. Toronto’s process tends to fall on the longer end; smaller municipalities may be faster.
Ontario Building Code Requirements for Garden Suites
Your garden suite must meet the Ontario Building Code (OBC) — the same code that governs new homes. Here are the key requirements homeowners should understand:
Minimum ceiling height. Living areas must have a minimum finished ceiling height of 2.3 metres (approximately 7 feet 6 inches). Bathrooms and hallways can be slightly lower.
Bedroom egress windows. Every bedroom must have a window large enough for emergency escape — minimum 0.35 square metres of unobstructed opening. This is a life-safety requirement and is non-negotiable.
Fire separation. If the garden suite is within a certain distance of the main dwelling or the property line, fire-rated construction is required on the facing walls. Your designer will calculate the specific requirements based on your lot layout.
Insulation and energy efficiency. Garden suites must meet current OBC energy efficiency standards, which typically means R-24 walls, R-50 attic, and high-performance windows. As of 2026, full-height insulation on basement or crawlspace walls is also required.
Plumbing and electrical. The suite needs its own complete plumbing system (kitchen sink, bathroom fixtures, water heater) and a properly sized electrical panel with its own service or sub-panel from the main house. All plumbing and electrical work requires inspections.
Smoke and carbon monoxide alarms. Interconnected smoke alarms and CO detectors are required in all sleeping areas, hallways, and any room with a fuel-burning appliance.
Accessibility. While full accessibility isn’t required for all garden suites, designing with accessibility in mind — wider doorways, a step-free entrance, a main-floor bathroom — significantly increases the suite’s versatility for aging-in-place or multi-generational use.
Common Mistakes That Delay Garden Suite Projects
We’ve seen homeowners lose months — and thousands of dollars — on avoidable mistakes. Here are the most common ones:
Starting construction without a permit. This is the most expensive mistake. If the City discovers unpermitted work, you’ll face stop-work orders, fines (up to $25,000 for homeowners in Toronto), and potentially be required to demolish and rebuild to code. A permit protects you — never skip it.
Assuming your lot qualifies without checking. Not every lot meets the minimum size, frontage, or servicing requirements for a garden suite. A 10-minute call to your municipality’s planning department — or a consultation with your contractor — confirms eligibility before you invest in design.
Hiring a contractor before designs are permitted. Some homeowners sign a construction contract and set a start date before the permit is approved. If the permit takes longer than expected — or requires design revisions — you’re paying for a contractor who can’t start.
Ignoring servicing requirements. Connecting the garden suite to municipal water, sewer, and hydro requires site servicing work that many homeowners underestimate. Sewer connections in particular may require a licensed plumber to install a new lateral line, which involves excavation and City inspections.
Underestimating the timeline. From design to completed construction, a garden suite takes 8 to 14 months. Homeowners who expect to be done in 3 to 4 months end up frustrated. Set realistic expectations from the start. At T-ROC, we lay out the full timeline — every milestone — before any work begins. Learn about our process and how we keep every project on track.
Is a Garden Suite Right for Your Property?
A garden suite makes the most sense when your lot has enough space, your goals include rental income or multi-generational living, and you’re prepared for the 8-to-14-month process. For homeowners in Markham, Vaughan, Richmond Hill, and across the GTA, the regulatory landscape has never been more favourable — Bill 23 removed the biggest barriers, and municipalities are processing applications more efficiently each year.
If you’re weighing a garden suite against a basement apartment, they’re not mutually exclusive — under Bill 23, you can potentially have both (three units total on one lot). A basement suite is faster and less expensive to build; a garden suite offers more privacy and typically commands higher rent. Many GTA homeowners are building both to maximize their property’s income potential.
At T-ROC, we build garden suites and ADUs across the Greater Toronto Area — from compact 500-square-foot studios to full 900-square-foot two-bedroom suites. Explore our ADU and garden suite construction services to see what’s possible on your property, or request a free estimate to get started.
Frequently Asked Questions
Do I need a rezoning to build a garden suite in Ontario?
In most cases, no. Under Bill 23 (More Homes Built Faster Act), garden suites are permitted as-of-right on most residential properties connected to municipal water and sewage in Ontario. You still need a building permit, but the costly and uncertain rezoning process has been eliminated for qualifying properties.
How big can a garden suite be in Toronto?
In the City of Toronto, the maximum garden suite footprint is generally the lesser of 10% of the lot area or 60 square metres (about 645 square feet), though larger lots may allow up to 90 square metres. The maximum height is 6 metres. Other GTA municipalities have similar but slightly different limits — check your local bylaws for specifics.
How long does it take to get a garden suite permit in Ontario?
Complete building permit applications for garden suites are typically approved in 8 to 16 weeks, depending on the municipality and the complexity of the project. Toronto tends to fall on the longer end. Submitting a thorough, complete application with all required drawings is the best way to avoid delays.
Can I build a garden suite and a basement apartment on the same property?
Yes — under Bill 23, most residential lots in Ontario can have up to three units: the main dwelling, one interior secondary suite (such as a basement apartment), and one detached accessory dwelling unit (garden suite). This allows homeowners to maximize rental income from a single property.
Do I need to provide parking for a garden suite?
No. Under Bill 23, Ontario municipalities can no longer require additional parking spaces for accessory dwelling units including garden suites. This is a significant change that makes garden suites feasible on smaller urban lots where adding a parking space would have been impractical or impossible.