Do I Need a Building Permit for a Secondary Dwelling Unit in Ottawa?

Written by

ogcadmin

Published on

August 18, 2026

Yes. Adding a secondary dwelling unit in Ottawa requires a building permit before you begin, without exception. The City's guidance is unambiguous: if you are adding or building a unit in an existing dwelling, you need a building permit before proceeding.

And the trigger is broader than most people expect. The permit is not driven by how much you are building. Even with limited or no work proposed, the change of use must be reviewed for compliance with the Ontario Building Code and other applicable law. A finished basement that gains a kitchen and a lockable door has become a second dwelling unit, and that is a permit.

This guide walks the process end to end. For the technical Building Code requirements themselves, see do I need a permit for a basement apartment in Ottawa.

Step 1: Confirm Zoning Before You Draw Anything

Permits are reviewed against zoning, so a zoning problem becomes a permit rejection. Confirm three things first: your zone code and any site-specific exception, how many units your lot permits, and whether you are on municipal services or private services.

This matters more than usual in 2026 because Ottawa has two zoning by-laws in effect at once. Applications deemed complete on or after March 11, 2026 must comply with both Zoning By-law 2008-250 and Zoning By-law 2026-50, with the most restrictive provisions of the two applying. Design to the tighter rulebook. See is my property zoned for a secondary unit in Ottawa.

Step 2: Work Out Who Can Take Design Responsibility

This determines your cost and your timeline, so settle it early.

One additional dwelling unit, where no other exists: a Building Code exception allows the homeowner to take design responsibility. The same exception applies to a permit to construct a coach house.
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 a registered designer, architect or professional engineer.

Even where you are allowed to self-certify, a registered designer usually pays for itself. Incomplete applications or improper design are the main reason permits get delayed or refused.

Step 3: Prepare Your Submission

A complete application generally includes:

The Application for a Permit to Construct or Demolish
Construction drawings, typically including a site plan, floor plans for all affected levels, a cross section, and details of the fire separation assemblies
Details of egress and means of escape, including window sizes and locations
Mechanical and plumbing details, including the duct-type smoke detector where a single furnace serves both units
Payment of the permit fee, which must accompany the application

On a septic lot, add confirmation from the Ottawa Septic System Office that the existing system can carry the extra load. Where the system cannot, an upgrade becomes part of the project.

Step 4: Apply

Additional dwelling unit applications can be submitted online through the City's Building, Planning and Land Development portal, accessed through a My ServiceOttawa account. You register once, then submit through the Building, planning and land development service widget.

In-person submission at a Building Code Service counter is still available but is by appointment only. If you want help before you file, Development Information Officers can be reached at 613-580-2424 extension 23434 or dioinquiry@ottawa.ca, with a response in two to three business days.

Step 5: The Other Permits You Will Need

The building permit is not the only approval. Budget for these:

Electrical permit from the ESA. Issued and inspected by the Electrical Safety Authority, separately from the City. A licensed electrical contractor can pull it and arrange inspections. See do you need a permit for electrical work in Ottawa.
Plumbing. Where the scope is plumbing only, the fee is $117 per application. Otherwise it forms part of the building permit review.
Mechanical. HVAC changes, new ductwork and ventilation are reviewed with the building permit.
Heritage permit if your property is designated or sits in a heritage conservation district, since a new separate entrance is exterior work.

Step 6: Fees, in Real Numbers

Alterations and renovations with no new floor area: $12.75 per $1,000 of construction value. Valuation is the total value of materials, labour, overhead and professional fees, not just what you pay a contractor.
New gross floor area (an addition): calculated using the City's Service Index rate multiplied by the proposed gross floor area. Where a project includes both, the two fees are added together.
Minimum fee: $117.
Change of Use: $126 per application.
Refundable inspection fee: $300 per unit for detached, semi-detached, row house and townhouse dwelling units.
Re-inspection fee: $100 per inspection.
Revision to permit: $12.75 per $1,000 of the value of the revised work, minimum $117.

On a $90,000 suite conversion, the building permit itself lands around $1,150 before the inspection fee and the other permits. That is a small line item against the project, which makes skipping it a poor trade. Full breakdown in Ottawa building permit fees for 2026.

Development charges

Development charges are usually the largest cost associated with creating a new unit, and this is where the news is good. Under provincial Bill 23 changes, additional residential units added to an existing home are generally exempt from development charges and parkland dedication. That exemption is the reason the economics of secondary suites improved so much.

Step 7: Review Timeline

Ottawa targets a first review within 15 business days under Council's approved enhanced service level. That is the first review, not approval. If comments come back, your clock restarts on the resubmission, which is exactly why a complete first submission is worth paying for. See how to speed up your building permit in Ottawa.

Step 8: Inspections

Work must be inspected at key stages of construction. Practical rules:

Book inspections 48 hours in advance to be sure an inspector is available.
Permit plans and specifications must be on site and available to the inspector.
Your inspector's name and phone number appear on the permit itself.
Missing a required inspection can mean uncovering and exposing completed work, or an order being issued.

Typical stages include framing, rough-in plumbing and mechanical, insulation and vapour barrier, and final. The ESA inspects the electrical separately.

What Happens If You Skip It

Starting construction before a permit is issued carries an administrative surcharge of 50 per cent of the calculated permit fees, up to $10,000, on top of the normal fee. Beyond the City's penalties, an unpermitted unit creates three practical problems: insurers may decline a claim arising from the work, lenders will not count the rental income, and the work has to be disclosed at resale. See can you sell a house with unpermitted work in Ottawa.

The Other Consequences Worth Planning For

Property taxes. MPAC may reassess your property after a unit is added.
Income taxes. Rent counts as income under the Income Tax Act.
Insurance. Notify your insurer or broker early. Your policy will likely need adjusting for the change in liability and value.

Let Us Run the Permit Process

Ottawa General Contractors handles zoning review, drawings, permit applications and inspections on every secondary dwelling unit we build, so nothing stalls on a technicality. See our income suite contractor services, our in-law suite renovations, or get a free quote.

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