Colorado rock climber and builder Andrew McMullin knew that he wanted to live in the picturesque mountains above Boulder. And he wanted a house that he could construct himself, mostly out of recycled materials.

One afternoon, while driving across Wyoming, listening to a recording of Jack Kerouac's On the Road and watching a train loaded with shipping containers, he found his inspiration. 

After 18 months of construction, McMullin moved into a 1,650-square-foot dwelling that includes two 40-foot-long, 9-foot-high steel containers that spent years on cargo ships before being retired. They flank a conventionally built two-story main living space perched above Nederland, about 18 miles up a canyon from Boulder. 

One of the containers, with large windows cut into the steel, holds the kitchen and the office; the other has two bedrooms and a bathroom. The corrugated steel, complete with dings and scrapes from heavy use on heaving seas, lends the house an industrial feel. 

In the steel-beamed main living space, McMullin poured a thick concrete floor and installed two clear, south-facing garage doors that allow the sun to warm the floor.

"When the sun is out and heating that floor, it can get toasty even if the temperature is below zero," says McMullin, a California native. "And then the concrete releases heat throughout the evening to keep the house at a relatively stable temperature without too much auxiliary heating."

The only other sources of heat are the wood stove, which he fires with leftover lumber from building jobs, and pipes that run water (from a water heater) through the concrete floor. He uses the floor's radiant-heating system only after the sun has failed to shine for a few days.

McMullin figures he didn't save money by using the containers, in part because it cost so much to haul them up to his mountain lot and install them with cranes. But he does get to live in a recycled retreat that feels like it was hammered together by Thor.