The two leading candidates for mayor of Vancouver are offering competing visions to increase the city's affordable rental stock, but some experts say neither plan offers a real solution.

Mayor Gregor Robertson and his NPA rival Suzanne Anton both want to encourage developers to build more rentals -- not just condominiums.

Anton says she'll cut red tape to make Vancouver friendlier for the real estate industry.

"The marketplace will build if the city creates conditions for them to build, makes it a little easier, a little faster, gives them more height where appropriate," she said.

Robertson created the Short Term Incentives for Rental Housing program -- also known as STIR -- which offers big savings for building rentals. He says the NPA's plan just won't work.

"I think we have to have all the tools working on this and not assume that the market's going to fix this. It hasn't worked to date, but that's been the NPA approach," he said.

The Vision Vancouver approach has convinced some builders to include rentals, but the units aren't subsidized. That means the rents are far from affordable.

Tsur Somerville of the University of B.C.'s Sauder School of Business says rents are high because real estate is pricey.

"We're expensive, we're unaffordable, so rental is going to be unaffordable here too unless it's old and worn down. That's where affordable rental housing comes from. No one builds new rental housing -- that's at the bottom of the market," he told CTV News.

"The way pricing works, you'd always rather build a condo building than a pure rental building."

He says government programs don't create rental stock -- condo owners do, by leasing their units. But those cost more than purpose-built rentals.

With a report from CTV British Columbia's Shannon Paterson