Thunder Bay zoning for small homes
City of Thunder Bay, a single-tier municipality. Population 108,843 (2021 census).
Backyard suite
A separate home in the yard of a house: garden suite, laneway suite or coach house, including prefab, modular or container units used this way.
Allowed with limits · Thunder Bay’s term: “backyard home”
A backyard home is permitted as a secondary use to a detached house, semi-detached house or townhouse in the urban residential zones, but only on lots with both municipal water and municipal sewer service, and not on undersized lots. Rural zones allow only one home per lot. [1][2]
- Where allowed
- Urban Low-rise (UL) zone and other urban neighbourhood zones as a secondary use (s.3.1.1(b)); the City guide says ADUs are allowed in the UL and Urban Mixed-Use (UX) zones [3]
- Number allowed
- 1 backyard home per detached house (Table 3.1.1a, UL zone) [3]
- Maximum size
- 40% of the main building's GFA or 50 m², whichever is greater; all accessory buildings and roofed structures max 100 m² GFA (Table 3.2.2) [3]
- Maximum height
- 4.6 m; maximum wall height 3.2 m (Table 3.2.2) [3]
- Setbacks
- Rear 0.6 m; interior side 1.5 m if less than 20 m from the front lot line, 0.6 m if 20 m or more; exterior side 3.6 m; front setback 1.5 m greater than the main building; not in any front or exterior side setback (Table 3.2.2, s.12.2(a)) [3]
- Separation from house
- 2.0 m (Table 3.2.2) [3]
- Servicing
- Only on lots with both municipal water service and municipal sewer service (s.12.2(b)); not on an undersized lot or a lot with a legal non-conforming main use (s.12.2(c)) [3]
- Parking
- 1 on-site parking space per home for buildings with 1–4 homes (City ADU how-to guide) [2]
Ontario-wide rule
Ontario law stops municipalities from banning one residential unit in a building ancillary to a detached house, semi-detached house or rowhouse on a parcel of urban residential land, as long as the lot has no more than three units in total. Municipalities still set most other zoning rules, but provincial law limits parking requirements, minimum unit size, lot coverage and separation distances. These units are also exempt from development charges and parkland dedication. [4][5][6]
Tiny home on a foundation
A small house as the main home on its own lot. The key rule is any minimum dwelling size.
Allowed · Thunder Bay’s term: “detached house”
The zone standards tables, including the Rural and Urban Low-rise zones, list 'Minimum GFA: No minimum'.
- Minimum dwelling size
- No minimum GFA (e.g. Rural Zone large-lot table and Urban Low-rise density tables) [3]
Ontario-wide rule
Ontario law sets no minimum total size for a house that is the main dwelling. The Building Code sets minimum room areas, so the smallest compliant dwelling is roughly 17.5 m² by the Province's own estimate. Municipalities may still set minimum floor areas for main dwellings in their zoning by-laws. The provincial ban on minimum sizes covers only additional residential units. [4][7][8][9][10][11][12]
Tiny home on wheels or park model
Living full-time in a tiny home on wheels or a park model home.
Not allowed · Thunder Bay’s term: “mobile house / recreational vehicle”
A 'home' must be within a building, and the by-law's definition of building excludes a mobile house and a recreational vehicle; no zone lists mobile houses as a permitted use. Temporary buildings may not be used for human habitation, and a garden suite is defined but not listed as permitted in any zone.
- Where allowed
- None found: 'Building' excludes a mobile house or a recreational vehicle; 'Home' excludes a recreational vehicle (Section 14 definitions) [3]
- Temporary garden suite
- Garden suite (temporary, portable, secondary to a detached house) is defined and is only permitted in zones where expressly permitted (s.12.1(d)); no zone lists it [3]
Ontario-wide rule
Ontario has no single rule for living full-time in a tiny home on wheels. A unit on wheels can count as a 'building' that needs a permit and must meet the Building Code once it stays in one place, is hooked up to services or is anchored. Park model trailers are recognized only as seasonal recreational buildings. Municipalities may allow a portable garden suite under a temporary-use by-law for up to 20 years, with extensions of up to 3 years each. [12][7][4][9][8]
Bunkie or sleeping cabin
A small sleeping building with no kitchen, usually beside a cottage or house.
Not allowed · Thunder Bay’s term: “detached accessory building”
Section 12.1(a) states that no detached accessory building or structure may be used for human habitation unless specifically permitted by the by-law, and no sleeping cabin permission was found. A detached unit would have to meet the backyard home rules.
- Approvals
- No detached accessory building or structure may be used for human habitation unless specifically permitted (s.12.1(a)) [3]
Ontario-wide rule
Ontario law has no rule written specifically for bunkies or sleeping cabins. Whether one needs a building permit depends on the Building Code Act's definition of 'building' and the Code's shed exemption. That exemption covers only storage-use sheds, so it does not cover a structure used for sleeping. Municipal zoning rules for accessory buildings still apply. [9][7][4][13]
Official links
Last confirmed October 2026.
Notes and caveats
Sources
- Thunder Bay’s guide to additional units
- City of Thunder Bay PDF (thunderbay.ca)
- Zoning By-law 1-2022
- Planning Act (Ontario e-Laws)
- O. Reg. 299/19: Additional residential units (Ontario e-Laws)
- Development Charges Act, 1997 (Ontario e-Laws)
- Government of Ontario PDF
- Build or buy a tiny home: Building Code requirements (Government of Ontario)
- Building Code Act, 1992 (Ontario e-Laws)
- O. Reg. 163/24: Ontario Building Code (Ontario e-Laws)
- 2024 Ontario Building Code (Government of Ontario)
- Build or buy a tiny home: permits and inspections (Government of Ontario)
- Building Code updates (Government of Ontario)
Not legal advice
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