Do I Need a Permit for a Basement Apartment in Ottawa?

Yes. A basement apartment is a new dwelling unit, and creating one always requires a building permit in Ottawa. There is no square footage threshold and no exemption for small projects.

The point most homeowners miss: the permit is triggered by the change of use, not by the amount of construction. The City is explicit that even where limited or no work is proposed, the proposed change of use must be reviewed for compliance with the Ontario Building Code and other applicable law. If you already have a finished basement with a bathroom and you are just adding a kitchenette and a lock, you still need a permit.

Measure These Three Things Before Anything Else

These are the requirements that determine whether the project is viable at all. Check them with a tape measure before you spend money on drawings.

1. Ceiling height: 1.95 m (6 feet 4 and three quarter inches)

A basement second unit is permitted to have a ceiling height of 1.95 m over the entire required floor area, including the route inside the unit leading to the exit. Measure from the finished floor to the lowest obstruction, which usually means the underside of the joists, or the bottom of a duct or beam if one runs through the space.

This is the single most common project killer in Ottawa's older housing stock. If you measure 6 feet 2 inches, your options are underpinning or bench footing to lower the floor, and that moves the project into a different budget category entirely.

2. An escape window that actually qualifies

A basement or ground floor means-of-escape window needs:

• An unobstructed opening of at least 0.38 m² (4.1 ft²)
• No dimension of the openable portion less than 460 mm (18 inches)
• The opening no more than 900 mm (2 feet 11 inches) above the floor or steps
• To open easily without the use of tools

If the window sits below grade, you need a window well sized so a person can actually get out of it. Enlarging a basement window opening is structural work and forms part of the permit.

3. Your house's age

If your house is more than five years old, it is classified as an existing house and you get meaningful flexibility, including the 1.95 m basement ceiling allowance. If it is less than five years old, new construction requirements generally apply and the numbers get stricter. Confirm with Building Code Services before assuming.

The Rest of the Building Code Package

Fire separation

You need a 30-minute fire separation between units and between units and common areas. If a renovation requires altering an existing floor or ceiling, that assembly has to become a 30-minute separation.

The separation can be reduced to 15 minutes if the entire house has interconnected smoke alarms, which is often the cheaper path. A typical 30-minute wall is 2x4 or 2x6 studs at 16 inches on centre, insulated, with half-inch drywall on both sides.

Smoke and carbon monoxide alarms

• Smoke alarms must meet CAN/ULC S531 and have a flashing light when activated.
• Required on every level of the house, outside sleeping areas, in each bedroom of the second unit, and in common areas shared by both units such as entrances and laundry rooms.
• Carbon monoxide alarms are required if the house has a fuel-burning furnace or an attached garage. Locate them near bedrooms and sleeping areas in the unit, and in the furnace room where that room is separate from the units.

The furnace duct detector

This one gets missed constantly. The Building Code allows a single furnace and a common duct system to serve both units, but for fire safety you have to install a duct-type smoke detector meeting the UL 268A standard in the main supply or return air duct. When it activates, it shuts down fuel supply and electrical power to the furnace, preventing smoke from being pushed from one unit into the other.

Worth considering going past code here. One furnace and shared ducts means cooking smells, smoke and noise travel between units, and one thermostat controls both. A second furnace is often worth the money in a rental.

Room sizes and windows

Minimum floor areas under the Building Code:

• Living area: 13.5 m² (145 ft²)
• Dining area: 7 m² (75 ft²)
• Kitchen: 4.2 m² (45.2 ft²)
• Combined living, dining and kitchen in a one-bedroom unit: 11 m² (118.4 ft²)
• Master bedroom without a built-in closet: 9.8 m² (95 ft²)
• Other bedrooms without built-in closets: 7 m² (75 ft²)
• A bachelor unit combining sleeping, living, dining and kitchen: 13.5 m² (145 ft²)

Window area, where the window is not being used as an exit: 5 per cent of floor area in living and dining rooms, 2.5 per cent in bedrooms. No windows are required in a kitchen, bathroom or laundry room.

Plumbing

At minimum you need hot and cold water supply, a bathroom with a sink, toilet and a shower or tub, a kitchen sink, and access to laundry (shared or in-unit). Two Ottawa-specific items:

• Separate water shut-off valves for each unit are required, so plumbing work in one unit does not cut water to the other.
• A backwater valve may be required if your property is in an area subject to flooding or sewer backup, which applies to a number of older Ottawa neighbourhoods.

A kitchen in a basement carries its own considerations. See do I need a permit to put a kitchen in my basement in Ottawa and kitchen vs kitchenette, since the distinction affects whether you have created a dwelling unit at all.

Electrical

Electrical work needs a separate permit from the Electrical Safety Authority, not from the City, and the ESA inspects it independently of your building inspections. Use a licensed electrical contractor, who can pull the permit and book the inspections. See do you need a permit for electrical work in Ottawa.

Ventilation and lighting

The bathroom and kitchen both need ventilation, either an exhaust fan or an operable window to the outside. Every room and space needs a light and a switch, with switches at both the top and bottom of stairs.

Who Can Prepare the Drawings

A Building Code exception lets a homeowner take design responsibility when adding one additional dwelling unit where no other additional dwelling unit exists, or for a coach house permit.

If you are adding two additional dwelling units inside the principal building, the person taking design responsibility must be registered under a Building Code Identification Number (BCIN). That means hiring a registered designer, architect or engineer.

Cost, Timeline and Inspections

• Permit fee: $12.75 per $1,000 of construction value, with a minimum fee of $117. Construction valuation includes materials, labour, overhead and professional fees.
• Change of Use permit: $126 per application, where that is the applicable route.
• Refundable inspection fee: $300 per unit for detached, semi-detached, row house and townhouse dwelling units. Re-inspections are $100 each.
• First review: targeted at 15 business days under Council's approved service level.
• Development charges: additional residential units added to an existing home are generally exempt under provincial Bill 23 rules.

Inspections happen at key stages, and plans must be on site and available to the inspector. Book 48 hours ahead. Skipping a required inspection can mean opening finished walls back up. Full fee detail in Ottawa building permit fees for 2026.

What Happens If You Skip the Permit

Starting construction before a permit is issued triggers an administrative surcharge of 50 per cent of the calculated permit fees, up to a maximum of $10,000, on top of the normal fee. Beyond that, an unpermitted suite can void insurance coverage, cannot be reliably counted as income by a lender, and has to be disclosed at resale. See what happens if you renovate without a permit in Ottawa.

Related Reading

• Do I need a building permit for a secondary dwelling unit?
• Do I need a separate entrance for a basement suite?
• Do you need a permit for a basement renovation in Ottawa?
• Do I need a permit for structural changes?
• Cost to add a kitchen to a basement in Ottawa

We Handle the Permit, Start to Finish

Ottawa General Contractors manages zoning review, drawings, permit applications and every inspection on the basement apartments we build. See our basement suite services and income suite contractor services, or get a free quote.

‍