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Trois-Rivières, QC suite & ADU rules

Permission first. Construction second.

City accessory-housing rules took effect February 28, 2025 and distinguish four dwelling forms. 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 Trois-Rivières 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

City accessory-housing rules took effect February 28, 2025 and distinguish four dwelling forms.

What local rules actually say

The city distinguishes family-only intergenerational suites outside the urban perimeter, small attached accessory units, larger attached accessory dwellings and detached accessory dwellings. Its city guidance says detached accessory dwelling proposals require a conditional-use authorization from council.

Important exceptions and the next step

A detached backyard unit is not covered by Québec’s temporary attached-unit override. The city added servicing-related development restrictions in specified sectors in May 2026; verify the zone, servicing and permit process.

How to verify an individual property

  1. Look up the legal property address and zone on the official Trois-Rivières 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 Trois-Rivières.

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

Internal additional unitConditional — verify
Detached garden / backyard unitConditional — verify
DuplexProperty-specific
TriplexProperty-specific
FourplexProperty-specific

Before you build: confirm the exact property, zoning and permit path with Trois-Rivières.

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 Trois-RivièresOpen 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: Trois-Rivières states that accessory housing rules are in force since February 28, 2025 and distinguish intergenerational, attached accessory and detached units; detached UHA follows conditional-use approval.

Remaining verification: Confirm eligible zone, conditional-use council authorization, servicing/development restrictions effective in 2026 and construction permit, not just the province-wide attached-suite provision.

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.