Thinking of Adding a Legal Basement Apartment? Here’s What’s Involved
With rising housing costs and growing demand for rental space, legal basement apartments—also known as secondary suites—are becoming an attractive option for homeowners across Ontario. Whether you’re hoping to generate rental income, create a multigenerational living space, or increase the resale value of your property, a basement unit can be a smart investment. But it’s not as simple as putting in a kitchen and calling it a day.
At MAB General Contracting Inc., we’ve helped homeowners across Stoney Creek, Niagara, Hamilton, Burlington, Oakville, Milton, Brantford, Mississauga, and the GTA plan and build code-compliant secondary suites—and we’re here to walk you through what’s involved.
What is a Legal Basement Apartment in Ontario?
A legal basement apartment (or accessory dwelling unit) is a self-contained living space within a single-family home that meets all Ontario Building Code, Fire Code, and local municipal by-law requirements. This includes having its own kitchen, bathroom, sleeping area, and a separate means of egress (a way to exit safely in an emergency).
Simply finishing a basement doesn’t make it legal for tenants. There are strict guidelines, and every municipality has its own rules layered on top of provincial standards.
5 Things You Need to Know Before You Start
1. Zoning and Local By-laws Matter
Not every property is zoned for a secondary suite. Before any construction begins, you’ll need to check with your local municipality—whether you’re in Hamilton, Mississauga, Niagara, or elsewhere in the GTA—to confirm whether basement apartments are permitted and what restrictions may apply (e.g., parking, lot size, entrances).
Tip: MAB handles this for you. We work with local inspectors and planning departments to determine what’s possible on your property.
2. Permits Are Non-Negotiable
Adding a basement unit requires permits—from building and plumbing to electrical and HVAC. Trying to bypass the system not only risks fines and delays, but it could make your unit unrentable or uninsurable.
Our team will prepare and submit all necessary plans to get your secondary suite permits approved.
3. You’ll Need to Meet Safety & Code Standards
This includes:
- Minimum ceiling height (generally 6’5″ to 6’11” depending on the room)
- Separate entrance (or a safe shared access)
- Fire separation and smoke alarms
- Proper egress windows
- Independent HVAC or adequate ventilation
If you’re in Burlington, Oakville, or Brantford, your city may have additional fire code or occupancy rules. Meeting these standards is essential for legal occupancy.
4. Soundproofing and Comfort Add Value
Beyond the legal requirements, a well-designed in-law suite includes insulation between floors, quality lighting, and thoughtful finishes to ensure the space is quiet, comfortable, and liveable. This is what separates a basic rental from one people want to stay in long term.
5. Separate Utilities or Shared?
Depending on your goals, you may want to meter utilities separately or keep them shared. Each has pros and cons, and this decision can impact layout and cost. We’ll walk you through the best option based on your home setup and future plans.
How MAB Can Help
We specialize in in-law suite construction and legal basement apartment conversions, handling everything from design, permits, and inspections to construction, waterproofing, separate entrances, and finishing. With over 25 years of experience working in Southern Ontario, we know what it takes to meet local standards—and do the job right the first time.
Whether you’re in Stoney Creek, Hamilton, Milton, Oakville, Mississauga, or anywhere in between, we’ve got you covered.
Ready to Add a Legal Basement Apartment?
Adding a legal basement apartment is one of the most effective ways to unlock income potential in your home—but only when done properly. Don’t risk costly mistakes. Let MAB General Contracting Inc. help you navigate the process from start to finish.
Book your consultation today and find out what’s possible on your property.
Contact us for a free quote
