Airbnb this week acquired Urbandoor, a company that provides "corporate rentals" for business travelers and new employees, typically rented for anywhere between a month to a year.

Why it matters: Airbnb, long-acquainted with tensions around home-sharing and short-term rentals, is now stepping into the latest housing controversy in its hometown of San Francisco.

The big picture: Furnished rentals for business travelers are nothing new. But local press reports that startup Sonder has inked a deal to operate most of the rental units in a new building in downtown San Francisco has brought the issue to the forefront.

What they're saying: Critics, including some San Francisco legislators, say that these companies are using a "loophole" in local regulations by having a minimum stay of 30 days to avoid the label of short-term rentals. At the same time, they're marketed as flexible and ideal for renters that only need housing for a few months.

“What we need is housing for people who will make San Francisco their home, who will enroll their children in our schools, who will become members of the community," San Francisco Supervisor Hillary Ronen in a statement to the SF Examiner. "Instead, developers are taking advantage of our efforts to streamline and expedite construction, and what does it get us? Not housing, that’s what.”

The other side: The companies argue there's a need for this type of medium-term housing.

"Year-long leases aren’t for everyone, including many long-term residents," said a Sonder spokesman to Axios via email. "As society becomes increasingly mobile and demands more flexibility, we believe agreeing to live in one place for twelve months at a time will become a thing of the past entirely."

He added that the company only operates in new or adaptive reuse buildings in appropriately zoned neighborhoods.

An Airbnb spokesman told Axios that the company is committed to helping protect affordable housing. Zeus Living, another San Francisco-based corporate rentals startup, did not respond to a request for comment.

Quick take: There's a growing number of renters looking for unconventional lease terms. Case in point, this San Francisco-based reporter received multiple inquiries from people looking for housing for just a few months in response to a recent ad looking for a long-term roommate.

The bottom line: In cities with severe shortages, controversies around housing are deeply emotional and delicate, regardless of whether companies are following local laws.

Editor's note: The story has been updated to correct that Sonder will operate most of the new downtown SF building's units (not that most of the company's units are in that building).