Mississippi Mills zoning for small homes

Town of Mississippi Mills, in the County of Lanark. Population 14,740 (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 · Mississippi Mills’s term: “additional residential unit (detached)”

An additional residential unit is permitted in a building ancillary to a detached, semi-detached or duplex dwelling in any zone that permits those dwellings, subject to size, distance and servicing rules in Section 8.16.

Maximum size: Gross floor area of an at-or-above-grade ARU limited to 40% of the gross floor area of the principal dwelling unit (s.8.16(3)(d)) [1]
Number allowed: Maximum two additional residential units per lot (three per lot with a detached dwelling in the Almonte urban settlement area on R1/R2 lots meeting R1 serviced lot size); maximum two ARUs in an ancillary structure [1]
Separation from house: Detached ARU must be within 40 metres of the principal dwelling unit [1]
Maximum height: Accessory building standards apply (Table 6.1A): 4.5 m in R1, R2, R3, LSR, V and RR zones; 12 m in A and RU zones [1]
Setbacks: Accessory building standards (Table 6.1A): 1.2 m from interior side (rear yard) and rear lot lines in R1, R2, R3, LSR, V, RR zones; 1 m in RU, A and similar zones [1]
Servicing: Must connect to the principal dwelling's water and sewer services; on private services at least one service must be shared; private-serviced lots in Almonte must connect to municipal services first [1]
Parking: One space per ARU; on a lot with a single or semi-detached dwelling it may not be in tandem with the principal dwelling's space [1]
Where allowed: Not permitted on lots legally non-complying for width or area, or where the existing residential use is legal non-conforming; lot must front on an improved municipal street [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 · Mississippi Mills’s term: “detached dwelling”

The base provisions for the Rural (RU), Rural Residential (RR) and R1 zones set no minimum dwelling floor area. Minimums apply only on certain site-specific exception lands, such as R1-1, R1-8 and R1-9.

Minimum dwelling size: No minimum dwelling unit area in Tables 12.2 (RU), 13.2A (R1) or 17.2A (RR); site-specific exceptions set minimums (e.g., R1-8: 93 m²; R1-9: 110 m²) [1]
Minimum lot size: RR zone: 4,000 m²; RU non-farm residential: 1 ha; R1 with municipal water and sewer: 450 m² [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][5][6][7][8][9][10]

Tiny home on wheels or park model

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

Needs approval · Mississippi Mills’s term: “mobile home / recreational vehicle / garden suite”

Mobile homes and recreational vehicles may not be used as dwellings except temporarily on a construction site. A mobile home may be used as a garden suite, which requires a site-specific temporary zoning by-law and an agreement with the Municipality.

Temporary garden suite: Section 8.7: permitted only where a site-specific temporary zoning by-law allows it; agreement registered on title for up to 10 years; one per lot; rear yard only; max height 4.6 m and 1 storey; max floor area 65% of the principal building's gross floor area; not permitted on a lot with an ARU [1]
Where allowed: Section 6.31: in a rural zone, a mobile home may be used as temporary accommodation for up to 24 months while a permanent dwelling is being built [1]
Approvals: Section 6.11: no mobile home or recreational vehicle shall be used for residential purposes except as temporary residence on a construction site; a mobile home may be used as a garden suite [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. [10][5][2][7][6]

Bunkie or sleeping cabin

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

Not allowed · Mississippi Mills’s term: “guest cabin”

Accessory buildings may not be used for human habitation. The by-law defines a 'guest cabin', but the consolidation does not list it as a permitted use in any zone.

Maximum size: 'Guest cabin' is defined as one storey, without kitchen facilities, with a maximum ground floor area of 23.2 m² (249.7 ft²), but it is not listed as a permitted use [1]
Approvals: Section 6.1(2)(a): an accessory building shall not be used for human habitation; s.6.15(1)(a): human habitation not permitted in any building accessory to a residential use [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. [7][5][2][11]

Official links

Last confirmed October 2026.

Notes and caveats

Read the July 10, 2026 office consolidation (newer than the April 20, 2026 consolidation in the inventory, https://www.mississippimills.ca/media/s4vmgkto/consolidated-zoning-by-law-april-20-2026.pdf). It includes the ARU provisions (s.8.16) and the Almonte three-ARU permission. The bunkie answer rests on a full-text search of the consolidation: 'guest cabin' appears only in the definitions. No ARU guide was found.

Sources

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