Do you need a permit to replace siding in Ontario?

For a straightforward like-for-like siding replacement, usually not — but the exceptions are the part worth reading.

The City of London lists replacing siding or windows as work that does not require a building permit, provided there are no structural changes. Most Ontario municipalities take the same position, because cladding replacement on its own does not alter the structure, the occupancy or the fire separation of the building.

That exemption is narrower than it sounds. A permit is required once the work touches structure. Replacing rotted sheathing across a whole wall, altering or enlarging a window or door opening, or replacing brick veneer all move the job out of the exempt category. The City of London specifically lists brick veneer replacement as permit-required work.

Not needing a permit does not mean the rules stop applying. London is explicit about this: even where a permit is not required, the work must still comply with the Zoning By-law and the Ontario Building Code. Spatial separation limits on a tight urban lot are the usual place this bites — the allowable percentage of unprotected openings and the required cladding performance depend on how close the wall is to the property line.

Heritage designation is a separate approval entirely, and it catches people out. If the property is inside a Heritage Conservation District, or individually designated under the Ontario Heritage Act, a change to a street-facing elevation normally needs a heritage permit before work starts — regardless of whether a building permit is required. London has several designated districts, including Bishop Hellmuth, Blackfriars/Petersville, Old East, East and West Woodfield, and Wortley Village–Old South. Check the property against the municipal register before anyone orders material.

Conservation authority regulation is another separate approval. Properties near a watercourse, a floodplain or a shoreline bluff can fall under a conservation authority permit even when the municipality does not require one.

The municipality that matters is the one the property sits in. Every lower-tier municipality in this region runs its own building department. St. Thomas, Strathroy-Caradoc, Middlesex Centre, Thames Centre, Central Elgin, South Huron and the rest each administer permits separately, and none of them are the City of London.

The practical rule: if the job is cladding coming off and cladding going back on, you are almost certainly fine. The moment the wall opens up structurally, an opening changes size, the building is designated, or the lot line is tight — call the building department before starting, not after.

This is general information about how the process works, not a determination about your property. The municipality is the only authority that can tell you whether your specific project needs a permit.

Written by the team at siding contractor in London, Ontario.