The rental boom now sweeping the Twin Cities has raised the bar for the kinds of amenities found in today's apartment buildings, with outdoor kitchens and roof decks among the offerings.

Renters, most of them in their 20s or early 30s, want hip places to socialize and entertain their friends. So apartment owners must up the ante and build trendier living spaces if they want to compete.

That was the message an expert panel delivered to members of the Minnesota Multi-Housing Association recently on the latest trends dominating the robust wave of apartment building. 

About 12,000 new units are in the development pipeline in the seven-county Twin Cities metro area. And vacancies stand at 2.8 percent -- a 12-year low, said Brent Wittenberg of the multifamily housing research firm Marquette Advisors.

The market is dominated by 25-to-34-year-olds who are renters by choice and are seeking the social benefits of living in a stylish apartment community with like-minded peers, he said.

Architect Noah Bly, whose firm UrbanWorks Architecture has designed several of the entrants in the new apartment wave, added that new renters are looking for modern, high-quality apartment product that differentiates itself through branding and availability of the latest amenities.

High on the list of the latter is "great outdoor spaces," he said. 

"That means fantastic courtyards, where the grills have become complete outdoor kitchens," he said. "There's fire pits and just a lot of activity outside in these outdoor areas."

One new project featuring such a maximized courtyard is the Residence at the COR in Ramsey, a 230-unit, luxury apartment project next to the coming Northstar Commuter Rail station in the city. UrbanWorks designed the building for Indianapolis-based developer Flaherty & Collins Properties, which broke ground on it this spring.

"Roof decks and green roofs are also prevalent," Bly added, citing his firm's work on StuartCo's Heritage Landing in Minneapolis' North Loop district. 

In that case, the owner responded to the trend of rooftop social areas in new buildings by adding one to its eight-story luxury complex on N. 1st Street, which was opened in 2001. It includes seating, a bar area, planters and a pergola.

Another example of "rooftop deck mania" is the renovation of the 1914-vintage Soo Line Building by Village Green Companies in downtown Minneapolis, which is set to include a 15-foot-tall club room, terrace lounge and bar area.

And don't forget the dogs. Once shunned by apartment owners, pet-friendliness is now touted as a key amenity. 

"I think during the recession there was an effort made to bring in tenants who had pets, and after that, it stuck," Bly said. "We're seeing dog runs and pet-care areas in the new buildings."

The Longfellow Station project at the site of the former Purina Mills plant in Minneapolis will have a dog run area and a dog-washing center along the front of the building when developer Sherman Associates begins construction this year on the long-planned 180-unit project.

Cutting-edge social and common spaces are indeed what really sells new apartments to modern renters, added another panelist, Brent Rogers of Greco Real Estate Development, builder of the recently opened, 216-unit Flux Apartments in the Uptown neighborhood.

That new building, designed by BKV Group, comes equipped with an elegant pub room and an Internet cafe complete with a demonstration kitchen, as well as an outdoor pool, lawn bowling area and "industrial-sized grills" in its courtyard.

"Our focus has been to put an efficient, well-designed unit together with great common spaces," Rogers said. "Renters are paying top prices for the common areas and what that means for their lifestyles."

Don Jacobson is a St. Paul-based freelance writer.