What are the rules for building a secondary dwelling unit in Ottawa?

In neighbourhood zones, Ottawa's new Zoning By-law sets how many dwelling units a lot can hold based on lot size and zone, and a lot without municipal water and sewer is limited to two.

Under the Ontario Building Code, a secondary unit needs its own entrance, a fire separation from the main unit (at least 30 minutes, or 15.9 mm Type X drywall on both sides for a basement suite in an existing house), smoke alarms interconnected so one sounds in both units, and code-sized egress windows. A basement suite in an existing house also needs at least 1.95 m of ceiling height, or 1.85 m under beams and ducts. We confirm your lot's limit and the entrance location before designing.