The Building Code Act of Ontario defines a building as:
- a structure occupying an area greater than 10 square metres (108 sq. ft.) consisting of a wall, roof and floor, or any of them or a structural system serving the function thereof including all plumbing, works, fixtures and service systems appurtenant thereto,
- a structure occupying an area of 10 square metres (108 sq. ft.) or less that contains plumbing, including the plumbing appurtenant thereto,
- plumbing not located in a structure, (c.1) a sewage system or
- structures designated in the building code. The Building Code Act states that: no person shall construct or demolish or cause a building to be constructed or demolished in a municipality unless a permit has been issued therefore by the Chief Building Official.
The Building Code Act also defines construct to mean the doing of anything in the erection, installation, extension, material alteration or repair of a building which also includes installation of a building unit fabricated or moved from elsewhere