Life-safety rules are code questions, not zoning shortcuts
Once a municipality confirms that the dwelling form is allowed, the construction still has to satisfy the code and permit requirements that apply in the province or territory. Fire separation, alarms, egress, stairs, heating and ventilation are technical subjects; this guide is a planning checklist, not a substitute for code design.
Use the code that is actually in force
The National Research Council publishes national model codes, but those model documents do not automatically become law. Provinces and territories adopt or adapt them, sometimes with municipal enforcement or additional local procedures. Confirm the active code edition and authority before relying on any dimension or assembly detail.
NRC — Codes Canada application FAQ ↗
Fire separation
A separate dwelling creates boundaries between spaces that can affect fire and smoke spread. The permit drawings may need to identify the required assemblies and penetrations around doors, ducts, pipes, wiring and other services. Do not assume an existing drywall finish proves the assembly is compliant.
Alarms and detection
Smoke and carbon-monoxide alarm requirements depend on the adopted code, fuel-burning equipment, layout and other conditions. The permit authority or qualified designer/electrician should determine the required locations, power/interconnection and inspection path.
Exits, egress and access
A suite needs a compliant means of escape under the applicable rules. The answer can involve doors, stairs, windows, travel paths and the relationship to the rest of the building. Because exact dimensions and exceptions vary by adopted code and building condition, use the approved plans rather than a generic internet measurement.
Mechanical systems matter too
Heating, ventilation and shared air systems can affect separation and safety. Plumbing, electrical and gas work can also require separate trade permits or inspections.