A group of civic-minded housing advocates that has spent months analyzing the city’s plan for affordable new units said although the intentions are good – the math does not add up.

The coalition, HousingNowTO, said they have found that three out of the four development sites earmarked as this year's priorities won’t be sustainable in the long-run.

The grassroots group has been reviewing the city strategy to build thousands of new affordable rentals on so-called “lazy” municipal lands – underused properties that could be transformed in an effort to address the city’s housing crisis.

The urban planners, data analysts and social planning experts said that denser development is required in order for the market-rate units to offset the cost of the subsidized ones for the near-century the city has established as its target.

“The way they chose to fast-track these sites was by applying all the old zoning rules to these sites,” data analyst Mark Richardson said. “Those zoning rules don’t match up with 99 years of affordability.”

“You need to make sure you’ve created enough density and enough units to support affordable housing all the way through to 2118.”

For example, the commuter parking lot declared surplus at 50 Wilson Heights Boulevard is the proposed site for 1,150 total new units, including 385 affordable ones. But, the group said in order for this development to afford decades of future maintenance, 1,600 units would be required to break even.

“We’re looking at densities, which raise the sites a couple of extra floors,” social policy expert Diane Dyson told CTV News Toronto. “But, it’s making sure that the economics of these work – that’s so important.”

“If we don’t do that, in five years the developers will be coming back and saying 'we couldn’t make it work, we need a bigger injection.’”

The group said they believe that the developments planned for 140 Merton Street and 705 Warden Avenue also require denser developments in order to be viable; at least 200 units per acre.

Of the city’s four current priority projects, they say only the housing plan for 450 new units at 777 Victoria Park Avenue will break even over the lifetime of the development.

“We’re not pushing the envelope enough [as a city], and we’re using outdated planning policies that are not reflective of the housing crisis that we’re in right now,” urban planner and designer Alexei Guerra said.

The group has redesigned the three development proposals and made a formal submission to CreateTO, the city’s real estate agency, calling for the affordable housing plans to be beefed up before they’re built - even if it means rezoning the properties.

A city spokesperson told CTV News Toronto that staff is still in the concept development and public consultation phase of the process and is reviewing development parameters for each site. Staff is preparing business cases to account for the density targets and demonstrate the revenue potential.

But the HousingNowTO group warns that if the city proceeds with the plans as-is, developers will either back out or the projects will fail in the long-run.

They warn that if the city proceeds with the plans as-is, developers will either back out or the projects will fail in the long-run.

“The math is the math. We can’t change it," Richardson said. “We just need to be braver, bolder, and more ambitious.”