Shed and accessory-building permits in Canada

Why the size threshold is only part of the answer

Municipalities often publish size-based building-permit exemptions for simple accessory structures. Those exemptions usually come with conditions, and zoning can still control where the structure is allowed.

Examples from official city guidance

Markham, Ontario: the city lists a detached single-storey accessory building with no plumbing and less than 15 m² among housing projects that do not need a building permit.

Greater Sudbury, Ontario: the city describes an exemption for certain sheds not more than 15 m², one storey, detached, used only for storage and without plumbing.

Windsor, Ontario: the city lists a detached accessory structure under 10 m² among projects that do not require a building permit.

Chilliwack, British Columbia: the city's single- and two-family guidance says accessory buildings over 10 m² require a building permit, while smaller accessory buildings require a siting permit.

Delta, British Columbia: the city identifies a limited exception for one accessory building under 10 m² when its conditions are met, while making clear that zoning requirements still apply.

Check these details before buying a shed

• Floor area
• Height and number of storeys
• Distance from lot lines and other buildings
• Foundation type
• Plumbing, heat or mechanical equipment
• Whether it will be used only for storage
• Electrical work
• Floodplain, easement or heritage constraints

Permit-free does not mean rule-free

A structure can be exempt from a building permit and still violate zoning, setbacks or another local bylaw. Treat the building-permit question and the property-placement question as separate checks.