St. Clair zoning for small homes

Township of St. Clair, in the County of Lambton. Population 14,659 (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 · St. Clair’s term: “second dwelling unit (in an accessory building / private garage)”

The by-law permits one second dwelling unit per detached, semi-detached or duplex dwelling, and allows it in a detached accessory building (private garage) only under a long list of conditions, including a 50–67 m² size range. It does not provide for free-standing garden suites as of right. Ontario's Planning Act (s. 35.1) overrides zoning provisions that would prohibit one unit in a building ancillary to a house on serviced urban land. [1][2]

Number allowed: 1 second dwelling unit per principal dwelling (s. 4.33.1.3) [1]
Maximum size: Second dwelling unit in an accessory building: minimum 50 m², maximum 67 m² gross floor area (s. 4.33.1.19) [1]
Maximum height: Must keep the maximum height for accessory buildings and may not be on a second floor or in a basement (ss. 4.33.1.25-26); detached accessory buildings in residential zones max 5 m (s. 4.3.4) [1]
Setbacks: Accessory building must meet the principal dwelling's side and rear yard setbacks; not in the front yard; not in a yard abutting the St. Clair River (ss. 4.33.1.18, 4.33.1.20, 4.33.1.27) [1]
Separation from house: In A1 or RS zones, no more than 10 m from the principal dwelling (s. 4.33.1.22) [1]
Parking: One additional parking space required for the second unit; no new driveway (ss. 4.33.1.9, 4.33.1.16) [1]
Servicing: Must connect to public services where available; private services subject to approval (s. 4.33.1.17) [1]

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. [2][3][4]

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 with limits · St. Clair’s term: “single detached dwelling”

The main residential and agricultural zones set a minimum gross floor area for single detached dwellings above 37 m². [1][5]

Minimum dwelling size: R1 and R2: 85 m² for a one-storey single detached dwelling; 70 m² on the ground floor for more than one storey (ss. 6.1.2, 6.2.2) [1]
Minimum dwelling size: A1 (Agricultural): 80 m² for a one-storey single detached dwelling; 70 m² ground floor if more than one storey (s. 5.1.2) [1]
Minimum dwelling size: A1-R (Non-farm Rural Residential): 85 m² one storey; 70 m² ground floor if more than one storey (s. 5.2.2) [1]

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. [2][6][7][8][9][10][11]

Tiny home on wheels or park model

Living full-time in a tiny home on wheels or a park model home.

Not allowed · St. Clair’s term: “travel trailer / mobile home”

Mobile homes are prohibited in any zone other than one that specifically permits a mobile home park, and no zone in the by-law text was found to permit one; travel trailers, truck campers and motor homes may not be lived in within a residential zone for more than 30 days in any 10 consecutive months. A 'dwelling' excludes travel trailers. [1]

Where allowed: s. 4.2(c): a mobile home is prohibited in any zone other than a zone which specifically permits a mobile home park [1]
Minimum dwelling size: Single-wide mobile home definition requires at least 65 m² floor area [1]
Approvals: s. 4.15: no travel trailer, truck camper or motor home shall be used for living, sleeping or eating accommodation in any residential zone for more than 30 days in any period of ten consecutive months [1]

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. [11][6][2][8][7]

Bunkie or sleeping cabin

A small sleeping building with no kitchen, usually beside a cottage or house.

Not allowed · St. Clair’s term: “sleeping cabin”

Accessory uses do not include any building used for human habitation except an approved second dwelling unit. 'Sleeping cabin' (10–30 m², no kitchen or bathroom) is defined but is only referenced in the definition of a recreational camp facility, not as a residential accessory use. [1]

Approvals: s. 4.3.1(b): accessory uses shall not include any building used for human habitation except a second dwelling unit approved by the municipality [1]

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. [8][6][2][12]

Official links

Last confirmed October 2026.

Notes and caveats

The by-law PDF cover reads 'Office Consolidation January 2024' (By-law 17 of 2003, prepared by County of Lambton), although the township's zoning page still says documents are current as of October 28, 2011 and to contact the Clerk to confirm. Zone standards (lot size, setbacks, height) are in a separate Table A (current as of 2011 per page). The second-dwelling-unit rules (B/L 11/13) predate the 2022 Planning Act s. 35.1 changes; the township's November 2024 Official Plan (found via search on stclairtownship.ca) has newer additional dwelling unit policies, but no implementing zoning amendment was found. Sleeping cabin definition appears in the by-law but no residential permission for it was found.

Sources

Not legal advice

Confirm with your municipality before you buy, build or move in.

Suggest a correction or source

Know of a by-law change, an exception or an official page we missed? Tell us. An editor checks every suggestion before the page changes.

Find help nearby

We don’t have a directory page for St. Clair’s area yet. These cover all of Ontario.

All Ontario municipalities