In summer 2025, the Saint-Jean-sur-Richelieu city council adopted a bylaw allowing the construction of detached accessory dwelling units on its territory, with an expected effective date in mid-September 2025, according to a report published by Le Canada Français.
What is changing in Saint-Jean
The City was already doing its part. Since August 2024, Saint-Jean-sur-Richelieu had allowed ADUs attached to the main residence, following the provincial as-of-right provision. With the new bylaw, it goes one step further by also allowing detached ADUs, commonly known as backyard homes.
The context is straightforward: the City points to a rental vacancy rate below 1% and a housing crisis that must be addressed. The stated goal is to add gentle density without changing the character of existing neighbourhoods.
Why this decision stands out
This is where the nuance matters. The as-of-right provision of Bill 31, in force until 2029, only covers ADUs integrated into or attached to the main house. Detached units still depend on the municipality's bylaw, under Bill 16.
In other words, without a local decision like Saint-Jean's, a backyard home remains prohibited, even though provincial law has opened the door to other forms of ADUs. That is exactly what makes this kind of municipal move important.
Conditions to know
The bylaw regulates construction in considerable detail. Here are the main conditions reported by Le Canada Français, to be confirmed with the Urban Planning Department before any project:
- Zoning. Detached ADUs are not allowed in agricultural zones.
- Only one ADU per lot, whether integrated, attached or detached.
- Separate building, to be located at the rear or side of the lot, with minimum setbacks.
- Main residence. The single-family house must be occupied by the owner. If the owner rents out the main house, they must then live in the ADU.
- Self-contained. The ADU must have its own sanitary facilities and its own kitchen.
- Foundation. A compliant concrete foundation is required.
- Area. The detached ADU cannot exceed 50% of the building footprint of the main building.
- No cellar or basement.
- Access. A pedestrian path (concrete or paved walkway) must connect the ADU to the street or to a parking area.
- Address. The ADU must be assigned a separate, clearly visible civic number or suffix.
These rules clarify a point that is often vague: in Saint-Jean, a detached ADU is not a makeshift habitable shed. It is a true second dwelling, designed and built as such.
In practice, for a Saint-Jean homeowner
For a family that owns a single-family house in a residential area, the decision opens up real possibilities. Housing an aging parent or a young adult in their own space, a few steps from the family home, becomes feasible from a regulatory standpoint. For an owner who wants to generate rental income while staying at home, a backyard home rented long term also becomes one of the possible options.
The main-residence condition is worth remembering: this is not an investment vehicle separate from family life, it is a tool for owner-occupants.
Key takeaways
Saint-Jean-sur-Richelieu joins the small group of Quebec municipalities that have taken a stand for detached ADUs through regulation. The decision is concrete, well-defined and enforceable. It also points to a broader truth: when it comes to ADUs, it is often the municipality, and not provincial law alone, that shapes what is feasible on your lot.
Before any project, confirm the conditions and procedures with your City's Urban Planning Department.