ANYONE WHO SURVIVED dorm life or housemate negotiations knows sharing space can be tricky. (The ribbon around the doorknob means what?) But cohabitation has advantages: lower costs, shared resources, and that “sense of community” that Portlanders, in particular, seem to treasure.

In these post-boom times, a glance around the Portland business scene suggests more and more local businesses are shacking up, splitting space, and combining wildly varied enterprises. The payoff can go beyond cheaper rent: these businesses effectively invest in one another, giving each other promotional and logistical boosts.

“We call it ‘coopetition,’” says Mike Pullen of the Southeast shop Bamboo Revolution, which shares space with a coffee roaster to create one of this new breed of conjoined businesses. After checking out these three examples of Siamese capitalism, we call it smart.

Skylab & Project

An architecture firm bunks with a real estate developer.

Upstairs in the West End’s Blackbox Building—home to new indie-luxe retailers like Blackbird and Tanner Goods—Project and Skylab dissolve traditional office hierarchies. Hallways don’t have doors; glass walls make conference rooms transparent; interior walls run parallel, open at either end. The employees sit at undivided long tables. There’s even a wet bar. The two firms developed the building together, and hope a free flow between businesses—separated only by color-coded carpet—will spur further collaborations. “There’s an alchemy that comes with getting the right people together,” Project’s Tom Cody says. “And when clients come in, the office tends to elicit a romantic reaction. The most corporate of people covet this atmosphere.”

Saint Cupcake & Noun

A dessert shop and an eclectic retailer find a sweet spot.

The SE Belmont Street space that houses Saint Cupcake and Noun, a vintage and jewelry shop, is less about philosophy and more about practicality. Moving in together gave Saint Cupcake’s Jami Curl an easier way to open a second location for her already-successful business. For Noun’s Stephanie Sheldon, the established cupcake shop’s popularity “was the marketing plan. Every time Saint Cupcake gets a piece of press, it’s press for me even if my name’s not mentioned.” The one drawback: the idea of two completely different retail shops in one space still confuses some customers. Sheldon tells them, “It’s like a really small version of a mall. Think of me as J. Crew, and Saint Cupcake as the food court.”

Bamboo Revolution & Coava Coffee

Eco-minded furniture and flooring teams up with premium caffeine.

When Bamboo Revolution moved into a massive converted autoshop on SE Grand Avenue last July, Coava Coffee Roaster’s brew bar was part of the showroom plan. The design-build bamboo business envisioned the flowing, multitiered wood counter of the coffee bar as an object example of what it can do. According to Bamboo Revolution’s Pullen, Coava’s steady stream of espresso-sippers works “better than glossy ads in a magazine”; the coffee roaster brings hundreds of customers into his showroom each week. Pullen finds that collaboration goes further than competition. “We’re missing an opportunity when we say this is mine, mine, mine,” he says. “Collaboration is the future.”