Short answer
Saint-Jérôme publishes a detailed municipal additional-dwelling regulation page.
What local rules actually say
The city allows one additional dwelling inside an eligible detached or semi-detached principal residential building, in the basement, main floor, upper floor or more than one level. Its habitable area must be smaller than the principal home and work requires a permit.
Important exceptions and the next step
For wells/septic, municipal guidance requires conformity of private service systems. This page does not establish detached garden-home permission.
How to verify an individual property
- Look up the legal property address and zone on the official Saint-Jérôme zoning map.
- Confirm the proposed dwelling type: internal suite, addition, detached garden home or multiplex; these can follow different rules.
- Verify zone exceptions, lot size, servicing, hazard/heritage limits, any registered restrictions and the current amending bylaws.
- Ask the local planning/building office for the required written zoning confirmation and building permits before commissioning construction.
Québec temporary attached-unit rule (2024–2029)
A separate Québec measure runs from 21 August 2024 through 20 August 2029. It can allow ONE additional attached dwelling in an eligible detached house within the urban perimeter, despite ordinary local zoning, subject to statutory exclusions and possible municipal opt-out. It does not authorize detached backyard cottages and does not waive municipal permits, architectural standards, building safety or hazard and heritage protections.