Condo developers say they are concerned one of Valerie Plante's plans may hurt the economy.

The incoming mayor campaigned on a promise to force developers to set aside 40 per cent of their projects for social and low-cost housing.

That's an impossible target, said real estate developer Benjamin Sternthal of Kodem Inc.

“There are a lot of projects that simply won't get off the ground,” said Sternthal, who studied social housing and said he believes in its importance – but this is the wrong way to approach it.

“The spinoffs and jobs created from one construction site are phenomenal. Stats Quebec keeps coming out with (that) and when you ask what's the number one driver of the economy, it's construction, so to inhibit that industry is the worst thing you can do for the economy,” he argued.

During the English-language debate, Plante argued that no social housing was constructed in Ville-Marie in the four years Denis Coderre was in office.

Now that they are taking over control of city hall, Projet Montreal wants to change that.

“Twenty per cent social housing, 20 per cent affordable housing in all new developments and also we would like to see apartments with three or more bedrooms so that families can stay in the city. Right now these condos are too small,” said Cote-des-Neiges-NDG Mayor-elect Sue Montgomery, adding that rents are too high for many residents. “We have people in Cote-des-Neiges that are paying 80 per cent of their income on housing. That is unacceptable.”

She is not concerned developers will stop building.

“I think there are probably developers out there who recognize that not everybody out there has the same amount of money to spend. As a government, we have the responsibility to provide safe, clean, affordable housing for residents. It's a human right, so if one developer doesn't want to play, I'm sure we will find another developer that will,” she said.

Sternthal, however, said developers won’t be able to shoulder the weight.

“The real estate development industry alone can't afford what's being proposed,” he said.

Some social housing activists told CTV they aren’t convinced of Projet Montreal’s proposal, and say the best option is for the city to buy land and build its own social housing – though they also say there remains a shortage of units and they are looking forward to seeing how Plante’s plans are implemented.