In the past decade, Toronto’s downtown population has exploded by 20 per cent — but families have been moving out.

The 14-and-under population has dropped by almost six per cent, threatening inner-city schools with closure and decreasing economic diversity.

“It’s a vicious circle of gentrification that will Manhattanize Toronto,” warns Coun. Adam Vaughan (Ward 20, Trinity-Spadina). “We’re building condos where people can start families, but can’t raise families” since they must leave Toronto to buy more affordable homes, he says.

Vaughan is pushing an amendment to the city’s Official Plan that would require 10 per cent of buildings of 100 units or more to be family-sized. Some housing experts say what Toronto really needs is something called “inclusionary zoning,” which gives the city the power to make developers build cheaper housing units.

Builders balk at being forced to devote space to larger condos. They contend families won’t buy expensive flats when they can get a whole house at similar cost outside the city.

Inclusionary zoning, used in more than 40 U.S. jurisdictions, takes a slightly different approach. It allows the city to require that, say, 10 to 20 per cent of a private development be “affordable.”