Accessory Dwelling Unit Permit - London, Ontario

Housing and Building Standards Ontario 3 Minutes Read · published February 12, 2026 Flag of Ontario

Applying for an accessory dwelling unit (ADU) in London, Ontario requires checking both zoning rules and building permit requirements before starting construction or conversion. This guide explains the local steps, the departments that enforce the rules, typical application pathways and common compliance issues so homeowners can prepare plans, submit the right forms and avoid enforcement action.

What is an Accessory Dwelling Unit?

An accessory dwelling unit is a secondary self-contained residential unit on the same property as a primary dwelling. London provides guidance about ADUs including where they are permitted and basic requirements on its official information page City of London: Accessory Dwelling Units[1].

Do I need a permit?

Most ADU projects require a building permit and must comply with the Ontario Building Code and local zoning rules; structural changes, new services or separate units usually trigger permit and inspection requirements. For building permits and submission requirements see the City of London Building Permits page City of London: Building Permits[2].

You will generally need a building permit before converting space into a rental ADU.

Penalties & Enforcement

Enforcement of ADU, zoning and building permit requirements is handled by municipal By-law Enforcement and Building Services. The City explains complaint and enforcement processes on its By-law Enforcement pages City of London: By-law Enforcement[3].

  • Fines: not specified on the cited page.
  • Escalation (first, repeat, continuing offences): not specified on the cited page.
  • Non-monetary sanctions: orders to comply, stop-work orders and prosecution in court are described as enforcement options on the cited pages.
  • Enforcer: By-law Enforcement and Building Services investigate complaints and conduct inspections; use the City’s complaint and building contacts linked below to report or get guidance.
  • Appeals/review: appeal routes or timelines for specific orders or permit refusals are addressed case-by-case; specific time limits are not specified on the cited page.
  • Defences/discretion: defences such as prior permits, variances or reasonable excuse depend on the permit record and any approvals; procedural relief may require a planning application or variance.
If you receive a stop-work order, contact Building Services immediately to resolve inspections or permit issues.

Applications & Forms

The primary application route for construction or conversion to an ADU is a building permit application through City of London Building Services. Specific published form names or numbers for an ADU are not specified on the cited pages; applicants should use the standard building permit application and submit plans, drawings and applicable schedules as described on the building permits page City of London: Building Permits[2]. Fees are set by municipal fee schedules and may appear on the building permits or fees pages.

How-To

  1. Confirm zoning allowance for an ADU on your property and whether a minor variance is required.
  2. Prepare scaled plans showing unit layout, fire separations, exits and plumbing/electrical changes.
  3. Submit a building permit application with plans and pay applicable fees via the City of London permits portal.
  4. Schedule inspections at required stages and complete any conditions listed on the permit.
  5. Obtain final occupancy approval from Building Services before renting or listing the ADU.
Begin the permit application early—reviews and revisions take time.

FAQ

Can I rent out an ADU in London?
Yes, if the ADU complies with zoning, building code and permit conditions and you have final occupancy approval.
How long does a building permit take?
Timelines vary by complexity and completeness of the application; average review times are not specified on the cited pages.
Do I need a separate address or services?
Separate entrances and services may be required depending on the project; check with Building Services when preparing plans.

Key Takeaways

  • Check zoning and building permit needs before work begins.
  • Submit complete plans to reduce review delays.
  • Contact By-law Enforcement or Building Services promptly if you receive an order.

Help and Support / Resources

  1. [1] City of London: Accessory Dwelling Units
  2. [2] City of London: Building Permits
  3. [3] City of London: By-law Enforcement

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