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Opinion: Attractive Duos – Why We Need More Duplexes and Semi-Detached Homes

Michael Geller
April 20, 2015

I was born in England where people usually live in apartments, row houses (called terraced houses) – or, if they have a bit more money, semi-detached houses.

If they are wealthier still, they lived in fully detached houses, “sitting on their own grounds” as my late mother would often say, referring to the home in which she grew up.

Living in Toronto, I saw many semi-detached houses, especially in the poorer parts of the city. For those not familiar with the term, a "semi" is located on its own lot, but is attached by a shared party wall to another unit, also on its own lot.

Semi-detached houses are often identical to, the mirror image of, or very similar to their twin – but over time may change, since owners are free to make whatever modifications they choose. It is not uncommon to see older semi-detached structures with different coloured roofs on each side, or painted different colours. Some may have additions in the back; others will not. Some owners may choose to enclose a paved patio in the front, while the adjacent house has a garden.

The point is, although the houses are joined to one another, each has a separate freehold title and owners are free to make alterations – with one important exception.

They cannot do anything to their common wall that might interfere with the adjacent owner’s “right of support”. This obligation is secured by a “party wall agreement” registered on title.

While both sides of a semi-detached house are often similar or identical, this is not always the case. Sometimes the structure is asymmetrical and may appear like one large house from the street, rather than two individual units.

While both sides are usually constructed at the same time, this is also not always the case. For many years I judged the Canadian Housing Design Council Awards program. One year the jury was impressed with a submission for a semi-detached house outside of Quebec City. We decided to visit the site.

When we arrived I was surprised to discover only half had been built. The photographer had carefully chosen an angle to hide the exposed grey concrete block party wall. When I asked the applicant why he had submitted a building that was only half built he responded that he hoped to win an award so he could finance and sell the other half!

Semi-detached houses are not common in Metro Vancouver. However, in some locations we do find duplexes.

The term “duplex” can have many different meanings. In many Canadian cities it refers to a building with one unit built above another. Other cities use the term for any arrangement of two dwelling units located on a lot.

In Manhattan, it has a very different meaning. A duplex is a single unit within a larger apartment building spread over two floors and connected by an indoor staircase.

I consider a duplex to be any structure containing two units. While they may be one above the other, they may also be side by side, or one behind the other. However, both units are located on the same lot.

As a result, each unit is part of a two-unit strata-titled development with a corresponding agreement. A number of my friends have recently purchased duplexes without realizing they are buying into a form of condominium.

One of the attractions of a semi-detached or duplex unit is that it is generally smaller and more affordable than a detached house. This is particularly appealing to those who cannot afford a single-family house, or those wishing to downsize.

Depending on your point of view, an advantage of a duplex is that significant changes to the exterior cannot be made without the approval of the other owner. However, for many buyers, this is a disadvantage.

I believe there is a growing need for both duplex and semi-detached housing in Metro Vancouver and throughout British Columbia. We should be modifying zoning bylaws to allow “two-dwelling structures” in both existing and new neighbourhoods, since with good design they can often fit in nicely with larger single-family houses.

I hope this column will encourage their construction in years to come.

Michael Geller
Michael is an architect, planner, real estate consultant and developer with more than four decades of experience in the public, private and institutional sectors. Some of his notable projects include the redevelopment of the South Shore False Creek, Bayshore in Coal Harbour and UniverCity at SFU. He is an adjunct professor at Simon Fraser University and is an affiliate of the UBC Masters in Urban Design program. Michael is a well-known commentator on real estate and housing and an adviser to the City of Vancouver's Affordable Housing Task Force. He is also a past president of UDI Pacific and UDI Canada, and has been honoured as a Fellow of the Canadian Institute of Planners and a Life Member of the Architectural Institute of BC.