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Québec City, QC suite & ADU rules

Permission first. Construction second.

Québec City’s official additional-dwelling rules expressly address internal units and detached garden homes. The right answer still depends on your property and the proposed dwelling form.

Main home
Secondary / ADU
One property · more than one approval layer
Property address check

Check a Québec City property by address.

Use the address tool to locate the property. Municipal zoning, parcel overlays and permits must be verified independently; this guide is not a permit decision. Last source review: 2026-10-09.

Address matching is not zoning certification. A municipality must confirm zoning and any relevant lot restrictions.

Municipal source reviewReviewed 9 October 2026

Short answer

Québec City’s official additional-dwelling rules expressly address internal units and detached garden homes.

What local rules actually say

Québec City permits one additional dwelling per qualifying lot, including an internal/addition unit in an eligible detached home or a detached garden dwelling. The city also allows garden units associated with certain semi-detached, duplex and triplex residences subject to the applicable requirements.

Important exceptions and the next step

Its official guide limits an internal additional unit to at most 40% of main building floor area and a garden home to at most 80 m² and 75% of the main building footprint. These standards, siting rules and permits apply to the actual parcel.

How to verify an individual property

  1. Look up the legal property address and zone on the official Québec City zoning map.
  2. Confirm the proposed dwelling type: internal suite, addition, detached garden home or multiplex; these can follow different rules.
  3. Verify zone exceptions, lot size, servicing, hazard/heritage limits, any registered restrictions and the current amending bylaws.
  4. 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.

Can you build here?

What to verify before building in Québec City.

This is the simple build-direction summary. The exact property still has to meet its zoning, site, servicing and permit requirements.

Internal additional unitProperty-specific
Detached garden / backyard unitProperty-specific
DuplexProperty-specific
TriplexProperty-specific
FourplexProperty-specific

Before you build: confirm the exact property, zoning and permit path with Québec City.

Next planning steps

Confirm the property rules, then plan your project costs.

Official sources explain the possible permission paths; a property-level zoning review comes before budgeting and contractor quotes.

1 · BudgetEstimate renovation costs in Québec CityOpen the matching Home Cost Canada city page, then adjust the project and scope.Open cost planner →2 · ContractorFind a local contractorHomeSelect is a separate contractor-matching service. Use it after the zoning and permit path are understood.Start contractor match →

Planning sequence: rules → budget → written scope / contractor. Cost models and contractor matching do not determine whether the municipality will approve the work.

Municipal evidence check — October 12, 2026

What the reviewed official material supports: Québec City says one additional dwelling per eligible lot; a garden house may be associated with a detached or semi-detached one-, two- or three-unit building, with project-specific restrictions.

Remaining verification: Check the permitted form, the local zoning grid, 80 m²/75% garden-house guidance, setbacks, heritage review and city permit for the property.

Evidence level: Official municipal information. Full enacted-bylaw signoff: Not completed. Property approval: Not assessed. Use the official source links below before making any building decision.

How this guide was verified

Guide verification: Official-source research summary. This guide provides linked municipal research; a complete enacted-bylaw, zoning-map and amendment cross-check has not been documented for this municipality.

Property confidence: Not assessed. City-wide guidance does not confirm permission for a particular parcel. Check official zoning, overlays and permits. How verification works →

Official sources

Reviewed 9 October 2026. Municipal guides describe published rules only. Source consolidations may not include the latest adopted amendment. No site-specific approval is represented.