For Travis Price, an architect in Washington, D.C., a corrugated steel shipping container isn’t just a place to store goods, but also a good place to live.

Price, and his eponymous design firm, have used the 40 foot-long sea containers like giant Lego blocks to build three apartment complexes in Washington, D.C., a town that has a desperate need for affordable new housing, where the median rent for a one-bedroom apartment in September was nearly $2,250, according to apartmentlist.com, only behind Boston, San Francisco and New York.

Shipping containers are 8 feet wide by 40 feet long, so each one can create about 300 square feet of living space. When several of them are connected together, they can make a sizable horizontal or vertical living space.

“It’s the great new building block of the 21st century,” Price said.​

In fact, because they are so new, one potential downside is that because containers are mobile, it brings into question how to finance such projects, said Adam Day, an architect with AMR Architects Inc. in Little Rock, Ark., who recently pitched a container-home project to a developer. Mobile homes, or manufactured homes, aren’t always considered real property because, as their name suggests, they’re mobile, and thus some banks won’t lend a mortgage on a mobile home, unless the wheels are removed, the mobile home sits on a foundation and the utilities and the plumbing are connected. “If you don’t attach it to a permanent foundation, it might be difficult to get a mortgage,” Day said.

Container homes may have the same financing issue. Because of their mobility by truck or rail, they’re just as mobile as a mobile trailer home, Day said, which made financing for his project tougher. “We pitched the project as being able to be deconstructed later to build something bigger, but because of the ease of it being taken apart, the developer didn’t buy it,” he said.

Also, the economics for such container projects don’t always work out. Day proposed a dramatic two-story container apartment design to replace a downtown parking lot. Finding suitable containers wasn’t hard as Little Rock sits along the Arkansas River, which sees about 12 million tons of cargo shipped along its 450-mile long waterways a year. “We had an excess of containers in town, he said, which helped keep the building costs low, “but budgets always drive projects,” he lamented.

The design netted plenty of local design accolades but because the local costs of utilizing metallurgists and welders to join the containers and fabricate doors and windows and the unfamiliarity of the construction design compared with conventional carpentry costs ($115 a square foot) made it a tough sell to the developer. “We found that there was no cost savings by choosing to go with shipping containers and this was due to the cheaper labor pool in general along with familiarity and comfort of traditional wood construction,” he said.

Still, container homes can provide affordable living, and they can be relatively quick to build.

Price’s first project, a four-unit design of three stacked containers in Washington, D.C’s Edgewood neighborhood, was completed in 2014 and took just seven months to design and build. His latest project, a four-unit design that’s more bold with cantilevered containers sticking out in multiple directions, will replace a 1970’s-era Safeway in the city’s Brookland district when it’s completed next year. ​​

Price says the Spartan industrial look isn’t actually new, as it has roots in the German “Bauhaus” (which means “house of building”) design of the early 20th century, headed by architect Walter Gropius, who later influenced designers like Ludwig Mies van der Rohe with his square geometric designs and lack of ornamentation.

“The Bauhaus movement was all about the freedom to have light, air and a vista,” Price said. “But small can be more. Add a corner glass window and the room explodes” with light, he said.

Price says the advantage of the shipping container is that portions of the corrugated sides can be easily removed without robbing the container of its strength, which allows desired features like 9-foot tall floor-to-ceiling windows or split-sliding doors to be added easily on all sides, including the open doors, giving the container home plenty of light, unlike a mobile home, which can’t have large windows because the body of the home needs to be able to withstand the punishment of the road.

The corrugated steel is also stronger than vinyl siding or wood, and can be easily painted, or as Price prefers, sanded down to bare metal where it can oxidize into a natural rusted patina. “It’s the new brick,” he said.

But some concerns have been raised over how safe container homes are, given that the seagoing lockers have wood floors that are often treated with pesticides to prevent infestation, along with chemicals to prevent corrosion from the salt air.

AMR’s Day says for that reason, recycling containers needs to be done carefully. “Knowing the history of its previous contents is very important, yet difficult to verify,” he said. “Removing the floor is one way to alleviate the issue, however its a structural component of the container and therefore costly to replace making the containers profitability less desirable.”

The global economic slowdown might also help make shipping containers more available. Price notes that more than 2 million containers worldwide are sitting idle on docks, including about 750,000 in the U.S., according to the U.S. Maritime Administration .

Already, pre-fabricated container homes​, which typically sell for about $30,000, according to Appleton, Wis.-based MODS International, a distributor of container homes, have been used as emergency housing​ for storm victims, as they’re easy to transport by truck or rail, and can be placed with a forklift or crane. ​The U.S. Army Corps of Engineers has also used containers for military housing in Iraq and Afghanistan, and shipping containers are also used by fire departments for live fire training and flashover simulators.

The container could be one solution to an urban housing shortage. Some cities that lack enough affordable housing have lifted zoning restrictions to allow for accessory dwelling units, or ADU’s, that can be delivered and placed in backyards in a short period of time. Once plumbing and utilities are connected to a container home, the homeowner can start generating rental income and affordable housing to spring in up in neighborhoods otherwise in short supply. ​ In Washington, D.C., Price says, he can construct a container home for about $175 a square foot, compared with conventional construction costs of $225 a square foot, he said.

“The beauty of these houses is that the guy who works on it can afford to live in it,” Price said.

Indeed, just east of Los Angeles, in Midway City, Calif., American Family Housing, a non-profit group which combats homelessness broke ground in September on a 16-unit housing development for displaced veterans, joining together 54 shipping containers in a two-story complex that will be known as Potter’s Lane. Each apartment, designed by Paul Zaleski of SVA Architects, will have about 480 square feet of living space and will be completed by January 2017.

Container homes might be a good turn-key, drop-in accessory dwelling unit, but that doesn’t mean they’re always cheap. While a container can be bought or fabricated for about $3,000, a fully-equipped​, upscale ​unit can cost as much as $75,000 to $100,000 depending on fittings,​ insulating materials,​ wall and floor coverings and appliances, said Kelly Davies, an architect with Travis Price. What they do save, is time. Davies says that a multistory apartment structure made of shipping containers can be bolted together in the space of a few hours, taking just days to erect, rather than months.

“This is simple as snapping Legos together when you were a kid,” she said.

And when it comes to financing, Davies said that while some banks aren’t quite up to speed on the container as a home, it’s just a matter of time. “People want to live like this now, and while some banks might say no (to financing) others are going to say yes,” she said.

Day is also optimistic that the container home will catch on especially with millennial-age home buyers and apartment shoppers, who may want something more unique than a typical garden apartment or high-rise. “We’re getting a lot of phone calls about the project. The public was excited about it and the millennial generation I think is hungry for something like this,” he said.

Expect that 30-year mortgage rate to get even more expensive.

Daniel Goldstein is a personal-finance and real-estate reporter for MarketWatch.

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