Ontario now permits up to three additional residential units (ARUs) on many residential lots as-of-right under Bill 23 — but legal requirements are strict, and rules vary by municipality. Before you invest in a basement apartment or second suite, you need to understand what makes it legal, what regulators require, and which municipalities you can actually operate in.
Ontario's Additional Residential Unit (ARU) Framework
In November 2022, Ontario passed Bill 23 — the More Homes Built Faster Act and amended the Planning Act to establish the ARU framework. The intent was clear: unlock rental housing supply by making it easier for property owners to create legal second units.
The Provincial Permission
The framework grants as-of-right permission (no rezoning needed) for up to three total residential units per lot, provided:
The lot is within a municipal settlement area
The municipality has full water and sewer services to the property
The lot's zoning is for residential use
The permitted configurations are flexible:
Option 1: Two units in the principal building + one unit in an ancillary structure (garden suite, laneway house, detached coach house)
Option 2: Three units in the principal building only (no separate structure)
The Critical Caveat: Municipal Alignment
Here's where many investors stumble. Bill 23 provides provincial permission, but your municipality must have brought its zoning by-laws into alignment with the provincial framework. Some municipalities were slower to update than others, and a few pockets still have outdated requirements.
You must confirm with your local municipality's planning department that:
Your specific property and zoning allow ARUs
Your lot has adequate municipal water and sewer services
Your municipality has no restrictive by-laws that override the provincial standard
This is non-negotiable. A property that appears eligible at the provincial level may not be permissible in your neighbourhood. Many inexperienced investors have purchased properties expecting to add a basement apartment, only to learn the local municipality hasn't proclaimed the necessary zoning changes—or has additional requirements (lot size, setbacks, parking) that make the unit infeasible.
The Legal Requirements
If your municipality permits ARUs and you have the essential services, creating a legal second suite or basement apartment means meeting every one of these requirements. None can be skipped; all are enforced.
Building Permit
You must obtain a building permit before any work begins. This is not optional, and the permit triggers inspections at key stages (foundation, framing, electrical, final).
Ontario Building Code (2024 OBC)
The 2024 Ontario Building Code sets minimum standards for basement suites specifically:
Ceiling Height:
Minimum 1.95 metres (6 feet 5 inches) throughout all habitable rooms
Under beams, ducts, or other obstructions: minimum 1.85 metres (6 feet 1 inch)
If your basement has dropped ceiling areas or ductwork, you may not meet this threshold. Low-ceiling basements are often disqualified from legal suite conversion.
Egress Windows (Emergency Exit):
Every bedroom must have an operational egress window:
Minimum unobstructed clear opening of 0.35 m² (approximately 3.8 square feet)
No single dimension smaller than 380 mm (15 inches)
Maximum sill height from finished floor: 1,500 mm (59 inches)
If the window is below grade, you must install a window well. If the well is deeper than 600 mm (about 2 feet), you must add a permanently attached ladder or steps.
This is critical for egress in a fire. Many basement suites fail on this requirement because the homeowner cannot cut a large enough opening or achieve the proper sill height.
Fire Code Compliance
Your second suite must meet Ontario Fire Code standards:
Smoke alarms on every storey and in every bedroom (may be interconnected wirelessly)
Fire separation between the rental unit and the primary dwelling (typically a 1-hour rated wall and floor/ceiling assembly)
A careless partition that doesn't meet fire-rating standards will fail inspection and be ordered removed.
Electrical
All electrical work in the new suite requires an Electrical Safety Authority (ESA) inspection and permit. You cannot simply hire an unlicensed electrician. The ESA will verify code compliance; if it's deficient, the work fails inspection.
Municipal Registration or Licensing
Many municipalities, including the City of Toronto, require registration or licensing of rental units. If your property is in Toronto or another jurisdiction with a rental-unit registry, you must register the suite after obtaining the building permit and passing final inspection. Failure to register can result in fines and orders to cease operating the rental unit.
Parking
Municipal parking requirements vary. Some municipalities have waived or reduced additional parking requirements for ARUs; others still require a dedicated parking space per unit. Check your local requirements early—inadequate parking can be a deal-breaker for the project.
The Income Case
Why create a legal second suite or basement apartment? The primary motivation is income offset.
A legal basement suite rented out can generate monthly income that helps cover your mortgage, property taxes, utilities, and maintenance. Rental rates depend on finish, size, and location — check current CMHC rental market data for your municipality before underwriting any numbers.
This income doesn't eliminate your carrying costs on a $2–$4 million GTA property, but it meaningfully reduces them. In a rising-rate environment where negative cash flow is common, a legal suite is one of the few levers an owner can pull to approach break-even or slight positive cash flow.
The Rent Register: You Cannot Set Rent Arbitrarily
Here's a critical constraint: if your basement suite was first occupied after November 15, 2018, it is exempt from Ontario's rent increase guideline and you may increase rent to market rates at each tenancy turnover (or, in some cases, during a tenancy, subject to notice requirements). However, if it was first occupied before that date, it is subject to the rent increase guideline, which for 2026 is 2.1%—the maximum you can increase rent annually on an existing tenant without LTB approval.
Always use the Ontario Standard Lease (mandatory in Ontario) and keep records of when the unit was first occupied, as this determines your rent-setting authority going forward.
Common Pitfalls
Illegal Suites
Many properties in the GTA have "black-market" basement apartments—unregistered, unpermitted, without proper egress, fire separation, or electrical safety. They generate income and appear to work fine until:
An insurance claim is denied because the insurer discovers an unregistered unit
The mortgage lender learns of an illegal unit and calls the loan or requires its removal
A tenant is injured in a fire or egress emergency and sues
A city inspector arrives and issues an order to cease operations
The property fails inspection during a sale
The risk is asymmetric: an illegal suite might produce rent for years, but the downside—legal liability, mortgage acceleration, loss of the rental income stream—is severe.
Insurance and Financing Issues
Before you build or rent out a basement suite, confirm with:
Your home insurance provider: Does your policy permit a rental unit? If you don't disclose it and a loss occurs, the claim may be denied. If the insurer permits it, there may be an additional premium.
Your mortgage lender: Does your mortgage allow a rental unit? Some lenders restrict income-producing use. Others permit it but require it to be a legal, registered unit. If you breach this term, the lender can accelerate the mortgage.
Always get written approval from both your insurer and lender before renting out the suite.
Tenant Rights
Once you rent out a suite, your tenant has rights under Ontario's Residential Tenancies Act (RTA):
You must provide the Ontario Standard Lease within 21 days of occupancy
You may collect only a rent deposit (last month's rent); damage deposits are forbidden
You must provide 90 days' notice before a rent increase (if subject to the guideline)
You must maintain the unit in a state of good repair
Wrongful evictions and harassment are illegal and subject to LTB penalties
Many first-time landlords assume they can manage a tenant informally or without legal compliance. The RTA and LTB exist to protect tenants, and ignoring them is costly.
Frequently Asked Questions
Can I build a basement suite on any residential lot in Ontario?
No. You need (1) provincial ARU permission via Bill 23 (settled), (2) municipal by-law alignment and water/sewer services (varies by municipality), and (3) a property that meets Ontario Building Code standards (ceiling height, egress, fire rating, electrical). Not every basement qualifies. Confirm with your local planning department and a building contractor before purchasing or committing to the project.
How much does it cost to legalize a basement suite?
Renovation costs vary widely—typically $40,000–$100,000+ for a finished basement with egress windows, fire-rated partitions, electrical upgrades, and finishes. This excludes land cost and carrying costs during renovation. Material and labour prices in the GTA are among the highest in Canada. Get 2–3 quotes from licensed contractors before committing.
What if my basement is too low (under 1.95 metres)?
You cannot legally rent it out as a residential unit. A low basement disqualifies the property from ARU conversion under the Ontario Building Code. Some owners dig out the floor or excavate the ceiling area, but this is expensive and sometimes structurally unfeasible (especially if the foundation is deep or utilities are in the way). Budget $15,000–$50,000+ for excavation, or accept that the space cannot be legalized.
Do I need a separate entrance for a basement suite?
Not necessarily, but it's strongly recommended. A direct exterior entrance (egress stair, separate door) improves privacy, security, and lease enforceability. However, some properties have interior-only access. Interior-only access is legal if it meets egress requirements, but it makes tenant separation less clear and may reduce the suite's rental appeal. Confirm with your municipality and building contractor.
What happens if I rent out a suite without permits or registration?
You risk:
Insurance denial: If a loss occurs, your insurer may refuse to pay if you failed to disclose the unit.
Mortgage acceleration: Your lender may demand immediate repayment and take steps toward foreclosure.
City enforcement: The municipality may order you to cease operations or face fines and liens.
Liability: If a tenant is injured, you may face tort claims and criminal liability in a serious incident.
Loss of income: You lose the rental stream, and you may be ordered to allow the tenant to remain rent-free until conditions are corrected.
The short-term income is not worth the legal and financial exposure.
Can my tenant stay indefinitely if I charge "less than market rent"?
Yes—but the RTA applies regardless of the rent level. If you rent out the suite at a below-market rate as a favour to a family member or long-term friend, they are still a "tenant" under the RTA and have all associated rights (notice of termination, eviction protection, rent guideline limits if applicable). If you later want them to vacate, you must follow RTA procedures and serve proper notice. Informal arrangements are not binding in the eyes of the RTA or LTB.
How do I register my suite with the City of Toronto?
Visit toronto.ca and search "Rental Housing Licensing" or contact Toronto's Shelter Support & Housing Administration (SSHA). You'll need proof of the building permit, proof of final inspection, and a completed registration form. Check the City's website for current requirements and fees (which change periodically). Other municipalities have similar processes; check yours.
If I sell the property, does the new owner inherit the tenancy?
Yes. Once you have a legal, registered tenancy in place, it binds the property. If you sell, the tenant does not vacate; the new owner steps into your landlord role and must honour the existing lease and tenant rights. If you wish to avoid this, you must terminate the tenancy before selling, using proper notice and LTB procedures (e.g., an N12 for personal use requires one month's compensation to the tenant). Plan accordingly.
Disclaimer
This content is for general informational purposes only and does not constitute legal, tax, or financial advice. The rules for additional residential units are complex and vary by municipality. You must confirm all requirements with your local planning department, a qualified lawyer, a licensed building contractor, and your mortgage lender and insurance provider before proceeding. Property laws, building codes, and municipal by-laws are subject to change. Always verify current rules before investing.
Who Is Inna Gold?
Inna Gold is a REALTOR® with RE/MAX Experts in Vaughan, Ontario, and a specialist in investor real estate throughout the GTA. She brings deep knowledge of the Ontario rental market, tenancy law, and the evolving ARU rules that many new investors find confusing.
"I pride myself for being knowledgeable and invested in real estate; keeping up with market trends and having my clients' best interests at heart. I master negotiation and never push my clients beyond their comfort levels. Real estate is a true passion of mine. I want to help everyone find their dream home and have the best experience throughout the journey." — Inna Gold, REALTOR®, RE/MAX Experts
Inna Gold, REALTOR® RE/MAX Experts — 277 Cityview Blvd Unit 16, Vaughan, ON L4H 5A4 Cell: 416-500-0696 | Office: 905-499-8800 info@innagold.com | innagold.com
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