In short
It controls things like a basement apartment, a garden suite, a home business or an addition.
Check it before you buy if you have plans for the property. It can make or break them.
How zoning works in Ontario
Zoning by-laws are passed by each municipality under Ontario's Planning Act. They set what can go on a property (homes, shops, offices) and how big it can be: height, lot coverage, setbacks from the property lines, and parking.
Every lot in Ottawa has a zone code. Before you buy with plans in mind, check the zone and what it allows, because a building permit won't be issued for work that breaks the by-law.
Ontario's three-unit rule
Since the More Homes Built Faster Act, 2022 took effect on November 28, 2022, Ontario has allowed up to three residential units on most urban residential lots with full municipal services, without a rezoning. That could be a main house plus a basement apartment and a garden suite or coach house.
The City's rules on size, height, setbacks and building code still apply, and lots on a private well or septic can face tighter limits.
Ottawa uses the term additional dwelling unit for a second or third unit inside the main home, and coach house for a separate unit in a backyard building. Each still needs a building permit.
Ottawa's new zoning by-law
Ottawa City Council approved a new comprehensive zoning by-law, Zoning By-law 2026-50, on January 28, 2026, and enacted it on March 11, 2026. It replaces the 2008 by-law and is designed to allow more gentle density in neighbourhoods.
As of mid-2026, most of the new by-law is in force. Some parts were appealed to the Ontario Land Tribunal, and where a provision is under appeal, the stricter of the old and new rules applies until the appeal is resolved. Confirm the current rules for a specific address with the City before you plan.
When zoning doesn't fit your plans
If a project doesn't quite meet the rules, you can apply to the Committee of Adjustment for a minor variance. Bigger changes need a zoning by-law amendment. Both take time and are never guaranteed.
Common questions about zoning
How many units can I build on my lot in Ontario?
Ontario allows up to three residential units on most urban residential lots with full municipal water and sewer, without a rezoning. That could be a main home, a basement unit and a garden suite. Local rules on size, setbacks and the building code still apply, and some municipalities allow more, so check with your city.
How do I find the zoning for a property in Ottawa?
You can look up a property's zoning using the City of Ottawa's online zoning map or by contacting the City. The zone code links to the rules for that zone. Because parts of the new 2026 by-law were under appeal, ask the City which rules apply to the address you're considering.
Is Ottawa's new zoning by-law in effect?
Mostly, yes. Zoning By-law 2026-50 was enacted on March 11, 2026, and the Ontario Land Tribunal allowed the unappealed parts to come into force in July 2026. Where a provision is still under appeal, the stricter of the old and new rules applies. Check the City's zoning page for updates.
What is a minor variance?
A minor variance is permission from the municipality's Committee of Adjustment to depart slightly from a zoning rule, like a setback or height limit. The committee considers whether the request is minor and fits the intent of the by-law and Official Plan. Neighbours are notified and can comment.
Sources
General information for Ontario, updated October 2026. Not legal, tax or mortgage advice. Rules change, so confirm with your lawyer, lender or the source above before you rely on it.