Decks
Depends on scopeLondon requires a permit for decks greater than 0.61 m high. Its homeowner guidance also says a side/rear deck below 600 mm requires a permit when attached to the house, so attachment matters for low decks.
London, ON
Building permits in London
London says most renovation, construction and demolition projects require a building permit.
Official sources checked Sep. 28, 2026
Permit rules by project
Pick the project that matches your work. These are starting rules for London; property-specific zoning, heritage and trade approvals can still apply.
Sheds & accessory buildings
Check size / scopeLondon lists a shed greater than 15 m² or any size with plumbing as permit work; a shed less than 15 m² can be exempt when it is one storey, free-standing, storage-only and has no plumbing.
Basement renovations
Permit requiredLondon lists finishing a basement to create rooms/living space, basement apartments, excavation for headroom and basement walkouts among permit-required work.
Secondary suites & ADUs
Permit requiredLondon lists an additional residential unit / basement apartment among projects requiring a building permit.
Home additions
Permit requiredLondon explicitly lists additions to existing buildings as permit-required work.
Interior alterations
Depends on scopeLondon lists interior alterations among permit-required work, while cabinetry, painting and several like-for-like replacements are specifically exempt; scope determines the result.
Walls / structural work
Permit requiredLondon’s permit material covers structural work such as underpinning, structural alterations and enlarged/new openings as permit work.
Pools / hot tubs
Confirm with cityLondon has a swimming-pool fence compliance process, but the City does not publish one clear building-permit answer for every pool/hot-tub configuration. Confirm the enclosure and construction permit path for the property.
Garages / carports
Depends on scopeLondon lists a detached garage as permit work and requires permits for buildings/structures over 10 m² or of any size with plumbing; some small accessory structures have exemptions.
Plumbing / HVAC
Depends on scopeLondon requires permits for HVAC systems, altered furnace ducts and adding/removing/relocating plumbing fixtures, while same-location plumbing fixture replacement and certain furnace replacement can be exempt.
Fences
No building permitLondon explicitly lists a fence as work that does not require a building permit; fence and pool-enclosure bylaws can still apply.
Retaining walls
Depends on scopeLondon explicitly lists a retaining wall less than 1 m high as no-building-permit work. Taller walls generally require permit/engineering review; site conditions still matter.
Demolition
Permit requiredLondon states that most demolition projects require a building permit and provides a demolition permit application/clearance process.
Apply or ask London
Use the municipality’s permit office for current forms, fees, drawings and questions about your property.
Your application route
Open the official permit page ↗Use the official permit page to confirm project requirements, forms, fees and the current application process.
Good to know in London
- The city lists additions and additional residential units, including basement apartments, among common projects that require a permit.
- The permit review checks the Ontario Building Code, London zoning and any other required approvals before construction proceeds.
- Ontario cities administer building permits under the provincial code framework. A building permit does not automatically resolve zoning or every trade, conservation, heritage or utility approval.
Official sources
Use these official links to confirm the current rule for your London property.
View 3 official sources
Sources checked Sep. 28, 2026. Requirements can change; the municipality makes the final permit decision.
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