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Montreal, QC suite & ADU rules

One property, two approval layers.

An internal suite and a detached garden unit can trigger different site rules, so define the project before reading the approvals.

ZONINGBUILDINGSERVICESINSPECTION
Main home
Secondary / ADU
One property · more than one approval layer
General official routeReviewed 2026-09-14

Where to start a Montreal suite or ADU check

This Montreal entry has a general official permit/zoning route rather than a verified project-specific suite page. Use it to confirm the address, unit form and current approval path.

Open the official Montreal source ↗

A similar home elsewhere in Montréal region is not evidence of entitlement in Montreal; use the current local zoning and permit information.

Quebec: the provincial layer

Quebec’s current housing legislation creates a provincial accessory-housing right in defined circumstances, while municipalities retain important siting, construction, architectural, parking and land-development standards and can use available exemptions.

Quebec accessory-housing provincial framework ↗

Use this order before committing to a design

What kind of unit?

Start with the physical form of the second unit; zoning often treats a basement suite and a backyard unit differently.

Is the use allowed?

Start with what the zoning allows at this address. Variances, overlays or site-specific conditions can change the general rule.

Can the building comply?

A second dwelling can trigger code work in walls, ceilings, exits and mechanical systems even when the zoning is straightforward.

Can the site serve it?

The parcel has to support the unit physically as well as legally, including servicing, access and any required setbacks.

For a Montreal property, check permission before construction

Start with land-use permission, then move to building-code life safety, trade permits, servicing and the final inspection or occupancy path.

Treat suite status as a due-diligence item. Request records rather than assuming long-term use equals compliance.

Do not equate occupied with legal. Permit and inspection status can matter even when the unit has existed for years.

Official sources

General official routeMontreal — official permit/zoning route ↗Quebec accessory-housing provincial framework ↗

Reviewed 2026-09-14. Recheck the linked local and provincial sources before relying on a suite or ADU approval path.