As a marathon meeting on Lansdowne Park drags through its second day, city council opted to allow more housing units on the site, potentially opening the door to raise the height of one tower if redevelopment goes forward.

Coun. Glen Gower made the motion to axe a unit cap for housing development, saying it could make a "significant difference" by providing more money to fund the project and devote to affordable housing off-site.

It passed unanimously. That prompted Coun. Tim Tierney to withdraw his own motion to return a third tower to the plan after it was removed in the latest staff design for Lansdowne.

That design, released in early October, included one 40-storey tower and one 25-storey tower. Tierney said removing the maximum unit cap of 770 units could allow both towers to rise to 40 storeys instead.

Don Herweyer, the city's general manager of planning, real estate and economic development later confirmed that there is no planning impediment to building two 40 storey towers on the site, though the specifics will be up to the developer who wins the successful bid.

Gower said his motion could push the number of housing units to about 920. Tierney said that achieved the same effect as his three-tower idea: building as much housing as quickly as possible.

"It was all about the unit numbers," Tierney said. "I think that achieved the objective that I was looking for, to add more housing to the City of Ottawa. ... The more we can flood the market with more units the better."

Last month's design with fewer units came in response to concerns from some residents that there was too much density in the initial three-tower plan. Tierney acknowledged that raising the cap might not be "super popular" with some neighbours.

Coun. Ariel Troster said she preferred taller towers to more towers, given that it would preserve park space, which would be eliminated by a third tower.

"I think it's kind of a happy medium," she said.

Gower's motion also removes a minimum parking requirement from the Lansdowne 2.0 plan, which mandated 0.4 parking spaces per unit.

"It would create the ability for less or even no parking, subject to the market," said Herweyer.

The city expects to earn $39 million from selling air rights to a developer to build towers at Lansdowne. Initially staff wanted to devote 10 per cent of that to affordable housing, but council voted on Wednesday to boost that to 25 per cent, plus half of any earnings in excess of the $39 million estimate.

Staff said removing the unit cap and parking requirement provides "ultimate flexibility" to a developer, potentially increasing the value of selling air rights and providing even more money for affordable housing.

But all of that is contingent on the $419 million plan to redevelop Lansdowne moving ahead, and that decision will have to wait until council disposes of still more motions on the agenda this week.