Ontario Design Studio prepares BCIN-certified permit drawings for legal basement apartments in Mississauga. Basement apartments - also called second units, secondary suites, or additional residential units - are one of the most in-demand projects in the city, offering homeowners rental income and multi-generational living. They are also tightly regulated: the drawings must satisfy the Ontario Building Code, the City of Mississauga zoning by-law, and the Ontario Fire Code, and the finished unit must be registered with the City. We prepare the complete package and guide you through Mississauga's ePlans submission and second-unit registration from start to finish.
Is a Basement Apartment Legal in Mississauga?
Yes. Under Ontario's housing legislation, a second unit is permitted as-of-right in most Mississauga residential zones - you can add a basement apartment to a detached, semi-detached, or townhouse dwelling, and in many cases a garden suite as well. Parking requirements for second units have been reduced across the province. The unit must be self-contained, with its own kitchen, bathroom, and entrance, and it cannot be severed from the main house. A building permit and City registration are both mandatory before it is legal to rent.
Mississauga Basement Apartment Requirements (OBC)
To pass plan review and inspection, a Mississauga basement apartment must meet the following key requirements:
- Ceiling height: minimum 1.95 m (6′5″) in all habitable rooms - if your basement is lower, underpinning or bench footing can create the height
- Fire separation: a 45-minute fire-resistance rating between units, typically Type X drywall with resilient channels, plus sealed penetrations and self-closing fire-rated doors
- Egress windows: each bedroom needs an openable window of at least 0.35 m² (about 3.8 sq ft) that opens without tools or keys, per OBC Section 9.9.10
- Separate entrance: an interior shared vestibule or a dedicated exterior walkout entrance
- Independent ventilation & heating: the suite needs its own HVAC/ventilation design so it is not dependent on the upstairs unit
- Interconnected smoke & CO alarms on every level of both units
- Zoning & energy compliance: conformity with the Mississauga zoning by-law and SB-12 energy requirements
Planning a basement apartment in Mississauga?
Ontario Design Studio delivers BCIN-certified, OBC-compliant drawings and handles the ePlans submission. Call 416-558-9607 or request your free quote - most packages are ready in 5–10 business days.
The Mississauga ePlans Submission Process
Mississauga accepts building permit applications digitally through its ePlans portal, and the City enforces strict file standards - drawings must be uploaded as individual, unsecured, greyscale PDFs in landscape orientation. Our drawings are pre-formatted to those exact standards, so your application clears the pre-screen instead of bouncing back. A typical project runs:
- Zoning check & measurement - we confirm your lot conforms before drawing
- Drawing preparation - the complete, ePlans-formatted package in 5–10 business days
- ePlans submission - we complete Schedule 1 (Designer Information), upload the set, and respond to examiner comments
- Permit & inspections - you build, with City inspections at each milestone
Registering Your Second Unit in Mississauga
A permit alone does not make the apartment legal - Mississauga requires second-unit registration. After the work passes final inspection, you submit proof of ownership and the signed-off building permit to the City's second units department to receive a Registration Certificate. We prepare your drawings so both the permit and the registration requirements are satisfied in one pass, protecting your insurance coverage, financing, and resale value.
What's in Your Drawing Package
- Site plan showing the building, lot, parking, and any exterior entrance
- Existing and proposed basement floor plans with room dimensions
- Fire-separation details and a bedroom egress-window schedule
- Cross-section confirming ceiling heights and assembly
- SB-12 energy compliance and Schedule 1 designer form
- Zoning summary confirming conformity with the Mississauga by-law
Basement Apartment Costs in Mississauga
BCIN designer fees for a Mississauga basement apartment typically range from $2,000 to $4,000, depending on layout and whether structural work such as underpinning is involved. The City's municipal permit fee is additional. See our complete 2026 building permit cost guide for a full breakdown.
Mississauga Neighbourhoods We Serve
We prepare legal basement apartment drawings across Mississauga, including Streetsville, Port Credit, Cooksville, Erin Mills, Meadowvale, Malton, Lisgar, Churchill Meadows, Clarkson, Lorne Park, and Hurontario.
Related Services
- Legal Basement Apartment Permits - Ontario-wide
- Basement Separate Entrance Permits
- Basement Underpinning Permits
- All Building Permit Services in Mississauga
- Building Permit Drawing Cost Guide
- 2026 Basement Apartment Requirements Guide
Frequently Asked Questions
Can I have a legal basement apartment in Mississauga?
Yes. The City of Mississauga permits second units (basement apartments) as-of-right in most residential zones. You'll need to meet OBC requirements for fire separation, egress, ceiling height, ventilation, and energy compliance, obtain a building permit, and register the second unit with the City.
Do I need to register my basement apartment with the City of Mississauga?
Yes. After the work passes final inspection, you register the second unit by submitting proof of ownership and the signed-off building permit to the City's second units department to receive a Registration Certificate. An unregistered unit is not considered legal, even if it was built with a permit.
What is the minimum ceiling height for a Mississauga basement apartment?
The Ontario Building Code requires a minimum ceiling height of 1.95 metres (6 feet 5 inches) in all habitable rooms. If your existing basement is lower, underpinning or bench footing can lower the floor to create the required height.
How much do legal basement apartment drawings cost in Mississauga?
BCIN designer fees for a Mississauga basement apartment typically range from $2,000 to $4,000 depending on complexity, plus the City's municipal permit fee. Contact us for a free, fixed quote on your specific project.