Ajax zoning for small homes

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 · Ajax’s term: “detached accessory dwelling unit”

One detached accessory dwelling unit is a permitted use in all residential zones and in the Permanent Countryside and Agricultural zones, on a lot with a detached, semi-detached, linked villa or townhouse dwelling (s.4.4.2, as amended by By-law 23-2025). It must meet the accessory building standards; in the Greenbelt Plan Area it is limited to accessory buildings that existed on or before July 1, 2017 and to lots outside the Greenbelt Natural Heritage System. [1]

Number allowed: One detached accessory dwelling unit per lot; up to two attached units may accompany it (s.4.4) [2]
Maximum size: Ground floor area less than that of the principal dwelling; all accessory buildings together may not exceed 60.0 m², 10% of lot area, or the zone lot coverage (s.4.4.2 v, s.4.1.1 iv) [2]
Maximum height: 4.5 m; 6.1 m where the unit is above a detached garage accessed by a driveway to a street or lane (s.4.1.1 v) [2]
Setbacks: 0.6 m from any lot line unless otherwise specified; not in front or exterior side yards (s.4.1.1) [2]
Separation from house: Minimum 3.0 m from any other building on the lot (s.4.4.2 iv) [2]
Parking: No additional space for the first accessory unit; 1 space for each additional unit (Section 5) [2]
Where allowed: Not on lands determined hazardous by the Conservation Authority (flood or erosion limits); 1.2 m unobstructed path to a driveway, street or lane required (s.4.4.2) [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. [3][4][5]

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 · Ajax’s term: “detached dwelling”

The residential zone standards (Table 2) and rural zone standards (Table 13) set no minimum dwelling unit floor area for detached dwellings. [2]

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. [3][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 · Ajax’s term: “mobile home / trailer”

Section 4.21 states that no truck, trailer, bus, coach, streetcar body or structure of any kind, other than a dwelling unit erected and used in accordance with the by-laws, shall be used for human habitation, whether on wheels or a foundation. A mobile home dwelling is defined but is not listed as a permitted use in any zone, and the by-law contains no garden suite provision. [2]

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][3][8][7]

Bunkie or sleeping cabin

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

Not addressed

The by-law does not mention bunkies or sleeping cabins. Accessory buildings are capped at 60.0 m² in total and 4.5 m in height, and s.4.21 says no structure other than a dwelling unit may be used for human habitation.

Maximum size: All accessory buildings: 60.0 m² total, max 10% of lot area (s.4.1.1 iv) [2]
Maximum height: 4.5 m (s.4.1.1 v) [2]

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][3][12]

Official links

Last confirmed October 2026.

Notes and caveats

The by-law was read from the March 6, 2026 office consolidation PDF. No official Ajax page for additional or accessory dwelling units was found: a site search on ajax.ca and one web search turned up nothing. The by-law calls these units 'accessory dwelling units' (By-law 23-2025).

Sources

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.

Ajax zoning for small homes

Backyard suite

Ontario-wide rule

Tiny home on a foundation

Ontario-wide rule

Tiny home on wheels or park model

Ontario-wide rule

Bunkie or sleeping cabin

Ontario-wide rule

Official links

Sources

Suggest a correction or source

Find help nearby