Where Are SDUs Allowed in Ottawa?

Written by

ogcadmin

Published on

August 14, 2026

Secondary dwelling units are permitted right across Ottawa, in the urban core, the suburbs, the Greenbelt communities, the villages and the rural area. There is no part of the city where they are simply banned.

What changes from one part of Ottawa to another is not whether you can build one. It is how many units you get, how the unit has to be serviced, and what the parking rules do to your driveway. This guide maps those differences.

First, a Note on the Term "SDU"

"Secondary dwelling unit" is the term most Ottawa homeowners still use, and it is what the City called these units for years. The by-law language has moved on.

By-law 2023-435 renamed Section 133 of Zoning By-law 2008-250 to "Additional Dwelling Units and Coach Houses." The new Zoning By-law 2026-50 uses the same vocabulary, defining an Additional Dwelling Unit as a separate dwelling unit subsidiary to and located in the same building as an associated principal dwelling unit, plus a coach house.

So when you search the by-law, search for "additional dwelling unit," not "secondary dwelling unit." The three terms you will encounter:

Additional dwelling unit: a suite inside the principal building, such as a basement or attic apartment.
Coach house: an additional dwelling unit in its own separate building on the same lot.
ADU: an informal umbrella term covering both. See ADUs vs SDUs in Ottawa and secondary suite vs garden suite vs ADU.

Ottawa's Six Transect Areas

The new by-law organises the city into six transect areas on Schedule A1, and several rules key off which one you are in:

Area A, Downtown Core
Area B, Inner Urban
Area C, Outer Urban
Area D, Greenbelt
Area E, Suburban
Area F, Rural

Additional dwelling units are permitted in all six. The transect changes driveway width limits, front yard parking rules, coach house heights and a handful of other standards.

Urban and Suburban Ottawa (Areas A, B, C and E)

This covers the Glebe, Westboro, Hintonburg, Alta Vista, Nepean, Kanata, Barrhaven, Orleans, Gloucester, Stittsville and everything in between. Most of these lots are on municipal water and sewer, which is the best case:

Up to two additional dwellings, so three units total on the lot.
That can be two apartments inside the principal building, or one apartment plus one coach house.
No more than one of the units may be a coach house.
No minimum parking is required.

Two location-specific constraints in the dense inner areas. In Areas A, B and C the maximum driveway width is 6 metres, and an individual driveway is not permitted on a lot narrower than 6 metres, where any driveway must instead be shared with an abutting lot. That matters on the narrow lots common in older Ottawa neighbourhoods.

The Greenbelt Communities (Area D)

Additional dwelling units are permitted here as well. Two differences worth flagging: a parking space may be established in a front yard beyond the required front yard setback, which is not allowed in the urban transects, and coach house footprints are permitted slightly larger in the rural and Greenbelt area than in Areas A, B and C.

Villages (Manotick, Richmond, Greely, Carp, Osgoode and Others)

Village Residential zones V1 through V5 and the Village Mixed-Use zone permit additional dwelling units, generally to a maximum of three units on serviced village lots.

The village exception that catches people: Section 614 keeps a minimum parking requirement in the Village Residential zones, at one space per dwelling unit. Ottawa removed minimum parking rates almost everywhere else, but not here. That required space cannot be located in a required front or required exterior side yard, and front yard parking is not permitted in the V zones or VM even though it is allowed elsewhere in the rural transect.

Rural Ottawa (Area F)

Permitted, with the servicing rule doing most of the limiting. On a lot served by a well, septic or any private service, you are limited to one additional dwelling or one coach house, so two units total. You will need the Ottawa Septic System Office to confirm your existing septic can carry the added load, and upgrading the system is a real possibility.

Coach houses in the rural area have their own gates. Under Section 133 of the old by-law, a coach house is not permitted on a rural lot that is less than 0.4 hectares in area and not serviced by both a public or communal water system and a public or communal wastewater system. The new by-law carries forward similar servicing conditions in Section 701. Rural coach house height is generally capped lower than in the urban zones, though a building that also contains a garage parking space is allowed additional height.

One useful rural provision: in Area F, phased development is permitted, meaning a coach house may exist before the principal dwelling type is established, provided the servicing requirements are satisfied once all phases are complete.

Which Building Types Qualify, Everywhere

Location matters, but so does what is already on the lot. Section 133 permits additional dwelling units and coach houses on a lot containing a:

Detached dwelling
Linked-detached dwelling
Semi-detached dwelling
Townhouse dwelling
Duplex dwelling

For semi-detached, linked-detached and townhouse dwellings, the rules apply separately to each portion of the lot on which each principal unit sits, whether or not that parcel is severed. Each half of a semi can add its own suite.

Where the Answer Is Genuinely No

Environmental Protection (EP) and Greenspace (GRN) zones.
Industrial and transportation zones (IH, IL, IM, T1, T2).
Development Reserve (DR).
Lots where servicing cannot support another unit, which is a capacity question rather than a zoning question, and one that ends more rural projects than zoning does.
Properties with a restrictive site-specific exception, shown as a bracketed number after your zone code on GeoOttawa.

A Note on Pre-2005 Units

Secondary dwelling units were permitted before 2005 in the former municipalities of Cumberland-Urban, Gloucester, Nepean-Urban, Osgoode, Goulbourn and West Carleton. If you bought a home in one of those areas with an existing suite, the City is clear that all units existing before 2005 must still comply with the Ontario Building Code and the Ontario Fire Code. An old suite is not automatically a legal one, and that gap shows up at resale. See can you sell a house with unpermitted work in Ottawa.

Confirm Your Own Address

General permissions are a starting point, not an answer. Look up your zone code on GeoOttawa, note any asterisk (which flags zoning under appeal) or bracketed exception number, and confirm with a Development Information Officer at 613-580-2424 extension 23434 or dioinquiry@ottawa.ca. Step-by-step instructions are in is my property zoned for a secondary unit in Ottawa.

Build Your SDU With Ottawa General Contractors

We build secondary suites, in-law suites, garage conversions and coach houses across Ottawa and the surrounding villages. See our income suite contractor services or get a free quote.

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