Julien Smith, the CEO and co-founder of Breather, isn't afraid to admit that his business is boring. Founded in 2012, the company rents out temporary space in commercial buildings for an average of $30 an hour.

"I want to be as boring as possible as a company," he says. To be successful, "you want a service that is so completely mundane that customers don't think of it as technology anymore." 

On Wednesday, Breather announced that it would be retaining a key partnership with real estate firm Cushman & Wakefield, as it expands into five new markets over the next two months, including London, Los Angeles, Washington D.C., Chicago and Toronto. Cushman & Wakefield is the company's exclusive broker, and Breather will be working directly with executive director Sean Black, who represents tech startups WeWork, Foursquare, and Business Insider across locations.

The app is relatively easy to use: Individuals or teams--from entrepreneurs to musicians and church groups--can book space for as little as 30 minutes, or up to one day. Simply order up a room on the Breather website, iOs or Android app, and users be receive a private code that unlocks the space for the allotted time frame.

So far, the business model has proven to be attractive. In just four years, Breather has already expanded into five major markets in the U.S. and Canada. It has raised more than $27 million in VC funding from firms like Peter Thiel's Valar Ventures.

Presently, the company controls over 100 units, half of which are located in New York City. It's also roped in some high-profile business customers, including Facebook, Uber, General Electric and Buzzfeed. These clients were adopters of the new Breather for Teams feature, which lets corporate groups book space en masse.

"Breather has been incredibly helpful to Uber, both for offsite meetings with our teams and for servicing our driving partners on weekends with pop-up support centers,"  notes Josh Mohrer, the general manager of Uber in New York.

Breather is growing its units by about 10 percent each month, and Smith is adamant that "this is a service big enough to exist in any commercial building in America." Of note, and unlike startups similar fields (namely, Airbnb) the business has yet to run into significant regulatory problems.

"We don't encounter the problems of Airbnb because we're always there by the consent of the landlord," Smith explains. Though he concedes, taking on units that stay open overnight could pose an issue, since in theory, individuals could sleep there when they aren't supposed to.

Certainly, one has to wonder whether or not clients are potentially renting out breathers for sex, drugs, or other illicit activities. Although the company does not physically monitor the units, Smith insists that he hasn't run into any problems so far. Clients typically bump into the Breather cleaning crew on their way out of the space, and a large percentage of clients are repeat customers. 

Smith, who launched the company in his hometown of Montréal, Quebec, initially struggled to convince real estate partners of the market potential. "At the very beginning, we had to rent our own spaces. There was no sense that there would be a need for it," he recalls.

The company also faces the challenge of keeping tabs on the status of a building. In the event of a flood, for example, Breather would be responsible for moving the booked client or team to a new location.

To date, the app has logged "tens of thousands" of bookings, which Smith attributes to the simplicity of the process.

"Our operations are much simpler than a lot of other companies like us," he continues. "We're not an on-demand people company, we're a little vending machine for space. All we have to do is set up the vending machine and walk away."

Although most of Breather's engineers are still based in Montréal, Smith notes that the startup's headquarters are "moving over" to New York, a city that Smith has long known intimately.

"I had a long career before this, almost exclusively in the U.S.," he says. "I'm much more Americanized than almost any other Canadian you know," he says.