How do I make a basement suite legal in Markham?You need a building permit from the City of Markham, and the suite must meet the Ontario Building Code, the Fire Code, zoning rules and electrical safety requirements. Ontario’s Planning Act allows up to three units on most lots with municipal water and sewer, and Markham has proposed allowing up to four. A legal suite needs its own kitchen, bathroom and entrance, safe exits, fire separation and working smoke and carbon monoxide alarms. Existing suites built without permits can often be brought up to standard. Speak to the City’s building department and a qualified designer before you start.
A basement suite can help pay the mortgage, give aging parents their own space or house an adult child. Across Markham, many homes already have one, but not all of them are legal.
Michael John Lau, a REALTOR® with the Kaizen Real Estate Team, one of the most active real estate teams in Markham and York Region, asks for permit records whenever a listing advertises a second unit, because buyers, lenders and insurers treat a permitted suite very differently from an unpermitted one.
What Ontario and Markham allow
- Ontario: up to three residential units on most fully serviced lots where a detached, semi-detached or townhouse is permitted. That can include a basement suite and one detached unit, such as a garden suite.
- Markham: the City has proposed allowing up to three additional units, or four in total, on these lots, with exceptions for environmentally sensitive areas. A public meeting was held on September 9, 2025, under file PR 24 196906. Confirm the current status with the City at ARU@markham.ca.
If you are thinking about a separate building in the backyard instead, see which Markham neighbourhoods have the best lots for garden suites and coach houses.
What makes a basement suite legal
| Requirement | What it covers |
|---|---|
| Building permit | Issued by the City of Markham before work begins, with inspections along the way |
| Self-contained unit | Its own kitchen, bathroom, living space and entrance |
| Fire separation | Approved separation between units, including ceilings, walls and doors |
| Exits | A safe way out, such as a separate entrance or an exit that meets code |
| Alarms | Working smoke and carbon monoxide alarms, often interconnected between units |
| Ceiling height and windows | Minimum heights and window sizes for living and sleeping areas |
| Electrical | Work inspected under the Electrical Safety Authority |
| Zoning | Parking, entrance location and other City standards |
This is a summary only. The Ontario Building Code and Fire Code set the exact standards, and the City of Markham’s building department reviews each application.
Markham’s permit process, step by step
- Check zoning and status for your property with the City, including any heritage or conservation area rules.
- Hire a qualified designer who prepares code-compliant drawings for second units.
- Apply for a building permit and pay the permit fee.
- Build with inspections at each required stage, plus an electrical inspection.
- Close the permit with a final inspection, and keep the records for insurance, financing and resale.
Small projects often need permits too. See the permit rules every Markham homeowner forgets.
Buying or selling a home with a second unit?
Michael John Lau can help you check permit records, compare sales of homes with legal suites and plan your next step.
Book a consultationSearch Markham homesPrefer to talk? Call the Kaizen Real Estate Team at (647) 370-8885.
Planning the layout for the people who will live there
Think about who the suite is for before you design it. A suite for aging parents may need step-free access, a walk-in shower, good lighting and a bedroom close to the bathroom. A rental suite for a working tenant may need its own laundry, good sound separation and a private entrance. Shared laundry, parking and outdoor space should be planned up front, so everyone in the home knows what is theirs.
Sound and privacy are the most common complaints in two-unit homes. Insulation between floors, solid doors and separate heating controls cost more during construction but are hard to add later.
Costs, financing and return
Costs depend heavily on the basement you start with: ceiling height, existing plumbing, the entrance and how much fire separation work is needed. Get several written quotes.
- Development charges: Ontario law exempts most additional residential units from development charges. Confirm with the City.
- Financing: CMHC-insured refinancing can let eligible owners borrow up to 90% of the home’s value after adding a suite, on homes up to $2 million, with amortization up to 30 years. The federal Secondary Suite Loan Program announced in 2024 was cancelled in the 2025 federal budget, according to RE/MAX Canada.
- Return: There is no published Markham data on the typical return from a basement suite. Compare your total cost with realistic rent, taxes on rental income and the time you plan to own the home. Speak to an accountant about how rental income is taxed.
Impact on resale value
A legal, well-built suite can appeal to multigenerational families and buyers who want help with the mortgage. A suite built without permits can do the opposite: some lenders will not count the rent, insurers may ask questions, and buyers may discount the price for the cost of making it legal.
| Legal suite | Unpermitted suite | |
|---|---|---|
| Buyer confidence | Permit records available | Unknown safety and work quality |
| Lender treatment | Rent may help the buyer qualify | Rent often not counted |
| Insurance | Easier to insure | Possible coverage issues |
For more on what can hurt a sale price, see what lowers home value in Markham.
If you rent the suite
Ontario’s Residential Tenancies Act applies to most rentals in your home. Use the Ontario standard lease, follow the rules on deposits and rent increases, and keep the suite safe. Renting to family on informal terms still deserves clear written expectations. Ultimately, the decision is yours. The goal is to make sure you have all the information.
A second unit can change how a home works for your family, so it is worth doing properly from the start. Call the Kaizen Real Estate Team at (647) 370-8885 or book a consultation.
Frequently asked questions
Are basement apartments legal in Markham?
They can be, if they have a building permit and meet the Ontario Building Code, Fire Code, zoning and electrical requirements. Ontario allows up to three units on most fully serviced residential lots.
How many units can I have on my lot in Markham?
Ontario law allows up to three. Markham has proposed allowing up to four units on lots zoned for detached, semi-detached and townhouse homes, with a public meeting held on September 9, 2025. Confirm the current status with the City.
Do I need a permit for a basement suite in Markham?
Yes. Creating a second unit requires a building permit from the City of Markham, with inspections during construction and an electrical inspection.
Can I make an existing basement apartment legal?
Often, yes. A designer can assess what is needed to meet code, such as fire separation, exits and alarms, and you then apply for a permit to complete the work.
Does a legal basement suite add value to a Markham home?
A legal, well-built suite can appeal to multigenerational families and buyers who want rental income. There is no published Markham data on how much value it adds, so compare recent sales of similar homes.
Is there government financing for a secondary suite?
CMHC-insured refinancing can allow eligible owners to borrow up to 90% of the home’s value after adding a suite, on homes up to $2 million. The federal Secondary Suite Loan Program was cancelled in the 2025 budget.
Michael John Lau and Neeraj Moolchandani are licensed REALTORS® with the Kaizen Real Estate Team, eXp Realty, Brokerage, 9763 Markham Rd, Markham, ON L6E 1A4. Licence #4784577. Call (647) 370-8885. Sources include the City of Markham’s Additional Residential Units page and public meeting notice for file PR 24 196906 (September 9, 2025), a summary of Ontario’s Planning Act from public legal commentary, and RE/MAX Canada’s summary of federal financing programs. Confirm all requirements with the City of Markham before you build. This article is general information only and is not financial, legal or tax advice. Not intended to solicit buyers or sellers currently under contract with another brokerage.
