You may have heard or read some of the media coverage earlier this year when Ottawa’s first official coach house was nearing completion on Hartleigh Avenue in the Lincoln Fields area. It was approximately 500 square feet, or roughly the size of many new condo apartment units.

Coach houses have been permitted by the city of Ottawa since last fall.

If you’re not familiar with the term, a coach house is a modest detached residential unit built on the lot of an existing home or adapted from an existing structure, such as a detached garage. It’s a permanent structure with a foundation, along with water, sewage, electricity and gas services, and it must conform to the Ontario Building Code.

If your lot meets the city’s requirements to allow a coach house, there are size restrictions. To minimize impact in the neighbourhood, the units cannot be larger than 40 per cent of the square footage of the main property, and in urban areas they can be only one storey in height.

Last October, the city of Ottawa approved such units in response to provincial legislation that encouraged coach houses as a way to increase the stock of affordable housing. Before that, Ottawa residents were permitted to create secondary units inside their homes (such as a basement apartment), but were not permitted to build a second detached home on their lot.

The idea of a coach house is that the owners of the main residence could build one as housing for aging parents, for adult children who need somewhere affordable to live, or simply for rental income.

A coach house on your lot has the potential to increase the value of your property, because it offers a second residence that could offer rental income. But it also means your municipal taxes would be likely to increase, and your insurance fees would also be affected.

So even if the idea of building one of these mini-homes appeals to you, it’s not a decision to take lightly.

As the city says in its document for homeowners who are considering one, “significant costs can be incurred” in building and servicing these homes. These costs “should be fully investigated before proceeding to detailed plans.”

In a radio interview, the developer who built the coach house in the Lincoln Fields area said the cost of building a typical coach house is between $200 and $300 a square foot. That would put the cost of a 500 square-foot coach house in the range of $100,000 to $150,000, though the developer said builders are looking for ways to reduce those costs.

The city of Ottawa developed a long list of rules and requirements for anyone building a coach house, rules that were developed after more than a year of consultation with experts and residents.

If you already have a basement apartment in your home, for example, you would not qualify to build a coach house.

Along with size limits, other rules require the water and other services to the coach house be connected to the services of the main home. A building permit is required, and roof patios are not permitted on coach houses. These are just a few of the rules.

The general goal of the rules, Ottawa city planners say, is for a “discreet” intensification of density, especially in neighbourhoods that were built entirely of single detached residences rather than a mix of residences and apartment buildings.

If you would like to learn more about the rules and costs that are involved, the city of Ottawa offers detailed information in a 32-page pdf document titled “How to Plan Your Coach House in Ottawa.”

You can go to and follow the links to that document. You can also call the city at 311 and ask to speak to a Development Information Officer if you would like to have your lot evaluated.

If you’re interested in selling or buying property in the Ottawa area, I’d love to chat about the current market and tell you about what I can offer, with more than 30 years of experience as a realtor. You can contact me through my website, at, where you can learn about the extensive services we offer to clients of Nancy Benson and Associates. Or you can give me a call at 613-747-4747.