Toronto's expanded multiplex era is coming. But how much housing will it actually provide?

Housing advocates have welcomed a recent Toronto council decision to allow construction of multiplexes across city neighbourhoods which had been dominated by single-family homes.

In Toronto, multiplexes are defined as low-rise housing containing two to four units within a single building. Until recently, zoning bylaws had restricted their presence in many parts of the city, but that changed after a May 10 council vote.

With a growing population, Toronto is embracing multiplexes as a tool to increase the housing supply in Canada's largest city. 

Yet questions remain as to how much new housing will actually emerge from this policy change and how affordable it will be — even if a greater supply and diversity of housing is sorely needed.

"We need a wider variety of housing types to accommodate diverse kinds of households," said Valerie Preston, an urban housing expert at Toronto's York University.

And while multiplexes may help deliver more varied housing options for larger families or others who need it, that doesn't mean they'll be inexpensive to develop, rent or buy.

"It will do nothing directly for affordability," said Preston, who expects multiplex development to have limited impact on the city's overall housing supply due to the costs of acquiring and developing property.

Toronto is expecting at least 700,000 new residents by 2051 and many complain of being unable to afford a place to live, with the average home costing more than $1 million. 

Increasing density, outside of condo towers which typically offer smaller units, has been welcomed by many housing advocates. 

The approach of adding a gentle level of density is one that other jurisdictions are exploring, both in Canada and elsewhere.

In British Columbia, the provincial government intends to bring forward legislation this year, which would allow three to four units on a single-family lot. Similar housing strategies have been enacted in some U.S. cities, and New Zealand.

But putting more housing on existing lots could drive up the value of the land below.

"Obviously, the more units you can put on a piece of land, the more it's worth," said Jane Londerville, a retired associate professor of real estate at the University of Guelph.

But she points out that not every suburban lot or structure will be appropriate for this type of development.