Property owners who use Airbnb on a commercial scale are draining the already limited rental housing supply in Vancouver and other major Canadian cities, according to a new study.

“Unlike a traditional hotel where they build a big building and they put a bunch of bedrooms in it, the supply of Airbnb short-term rentals is just drawing directly on the stock of available housing for local residents,” McGill University urban planning professor and lead author of the study, David Wachsmuth, told CTV News Tuesday.

The Montreal-based researchers studied Airbnb trends in Vancouver, Montreal and Toronto—Canada’s three largest cities.

While Airbnb claims it is designed for everyday people to rent their homes or spare rooms for extra income, the study found that 14,000 of the 81,000 listings across the three cities are being rented for more than 60 days a year, which makes them “unlikely to be rented to long-term tenants.”

A third of all properties in the three cities are “multi-listings,” which means the host is renting out two or more entire homes or three or more rooms within the same property. About 6,500 of those properties are entire homes that are being rented out for more than 60 days a year by multi-listing hosts—a combination the authors call the “unholy trinity.”

Although the owners of these properties make up only 10 per cent of Airbnb hosts, they are making a majority of the $430 million in annual revenue earned between the three cities, the study found.

Wachsmuth said the data revealed that a single host could be renting as many as 180 properties on the site.

“Some of these are big, large commercial property firms which are using Airbnb as a really efficient platform to rent out houses that could otherwise have local residents living in them year-round,” he said.

Conclusions 'unfair and untrue,' Airbnb says

Airbnb, however, is rejecting the findings, accusing the researchers of using “scraped,” insufficient data to make their conclusions.

“This author and others have used this sort of data to lead to misleading conclusions and make unfair and untrue statements about our host community around the world,” said Christopher Nulty, a spokesperson for the California-based company.

“The reality is the vast majority of people in Toronto, Vancouver and Montreal who are sharing their primary residences on our platform, they’re doing so for just a few nights each month and they’re making modest, but important additional income doing this.”

Nulty said Airbnb has been sharing “reams and reams” of data with local governments in hopes it will lead to regulation that protects rental markets and capitalizes on the tourism potential of those cities.

“We want to have an open and honest conversation about…how to best regulate home sharing, but that conversation has to be based on facts and has to use real data,” he said, adding that the study fails to account for the different scenarios in which a listing might fall under Wachsmuth’s “unholy trinity,” including people who have laneway homes or those who are away from their primary residence for most of the year.

“One author releasing a study that has not been peer reviewed and hasn’t even been published yet is not a good basis for a conversation around how home sharing works and the impact that it may or may not be having in cities across Canada.”

Nulty said the company doesn’t share revenue figures by city, but that Airbnb’s own economists have found that only 0.7 per cent of Airbnb listings in Toronto were rented out frequently enough to make more money than they would have from a long-term tenant.

The study, entitled “Short-term Cities: Airbnb's Impact on Canadian Housing Markets,” tells a very different story, however, with short-term rentals taking a significant, albeit reversible toll on local rental markets.

Wachsmuth said in some neighborhoods, full-time Airbnb listings make up two to three per cent of all rental housing in that area. That’s higher than the vacancy rate in many parts of these densely populated cities.

According the Canadian Mortgage and Housing Corporation (CMHC), the overall vacancy rate for Metro Vancouver was 0.7 per cent in 2016.

That number was 1.4 per cent among units with three or more bedrooms and 1.7 per cent in the Tri-Cities.

Other Vancouver neighbourhoods, however, such as the University Endowment Lands, had a zero per cent vacancy rate that year.

“The actual stock of housing available, if you’re looking for a place to live, has been dramatically shrunk by units being taken out of the market for short-term rentals,” Wachsmuth said.

The researchers say the strain on the rental housing supply can be easily alleviated if Airbnb and other short-term rental companies agree to properly enforce some simple rules.

The first involves placing a limit of one rental property per host.

“You shouldn’t be allowed to amass a whole portfolio of short-term rental properties that are going to be taking housing off the market for others,” Wachsmuth said.

The study also suggests Airbnb limits the number of days per year a host can rent out their property to 60 or 90.

“Airbnb can basically flip a switch on their website and say, ‘Once you’ve rented your apartment 60 days, on the 61st day we’re going to block you,’” the professor said.

The company has already placed a 60-day-per-year limit on its listings in Amsterdam.

“We think they can do it in Canadian cities as well,” he said.

With files from CTV Vancouver’s Allison Tanner and The Canadian Press