Permits in London
When a backyard shed, deck, or fence needs a building permit in London, Ontario, with the size cut-offs, coverage level, and source link.
Coverage
Municipal rule
Shed
London exempts a detached accessory structure under 10 square metres (about 108 square feet) from a building permit, and structures under that size are also exempt from setback requirements. At or above 10 square metres a permit is required.
Deck
A deck that is part of a principal entrance, or that is raised, needs a permit; a low deck that is not a main entrance generally does not. Confirm the height trigger on London's page.
Fence
Fences need no building permit; the fence bylaw caps height. Pool enclosures have their own permit.
The provincial baseline
Under the Ontario Building Code, a detached one-storey storage shed of 15 square metres (about 160 square feet) or less, with no plumbing, does not need a building permit. Anything larger, with plumbing, or attached to another building does. Zoning rules (setbacks, height, lot coverage) always apply even when no building permit is needed.
London permit questions
Do I need a permit to build a shed in London?
London exempts a detached accessory structure under 10 square metres (about 108 square feet) from a building permit, and structures under that size are also exempt from setback requirements. At or above 10 square metres a permit is required. Source: London building department, last checked 2026-06-24.
Do I need a permit for a deck in London?
A deck that is part of a principal entrance, or that is raised, needs a permit; a low deck that is not a main entrance generally does not. Confirm the height trigger on London's page.
Do I need a permit for a fence in London?
Fences need no building permit; the fence bylaw caps height. Pool enclosures have their own permit.
Source
From London building department, last checked 2026-06-24. London uses the lower 10 square metre cut-off, and ties the setback exemption to the same size.
This is a plain-language explainer, not legal or professional advice, and not the bylaw itself. Rules change and vary by zone within a city. Always confirm with your municipality's building department and the linked official page before you build. Decks and sheds near a conservation authority's regulated area may need a separate permit.
Other municipalities: Addington Highlands, Adelaide-Metcalfe, Adjala-Tosorontio, Admaston/Bromley. Or see every municipality.