When an adventure-loving couple decided to build a second home in the mountains for hosting friends, grown children, and—someday— grandchildren, they enlisted Californiabased Studio Bergtraun Architects to design it on a steep site in the Sierra Nevadas near Lake Tahoe. The firm took cues from the owners’ active, family-focused lifestyle to create a highly customized house on a challenging terrain.

Situated on a 23-degree slope that receives some of the region’s heaviest snows, the steelframe structure’s poured-in-place concrete-mat slab is pinned to the hill’s underlying granite. Lead architect Alex Bergtraun undertook a considerable study of the steep site to create a driveway with a less than 5 percent incline that would allow the clients to pull in easily and, after a long day of skiing, enter the mudroom without having to navigate stairs.

In order to accommodate different combinations of occupants, Bergtraun designed a two-level structure with a lower floor that can be closed off. There, built-in bunk beds (accessible via rock-climbing holds) and two bedrooms for the couple’s adult children flank a central family room. Upstairs, the main floor contains the master suite and kitchen, living, and dining areas. A concrete bridge extending off the kitchen provides a small patio for grilling but requires minimal snow shoveling. (Thanks to the installation of climbing hooks on the edge, it also provides a platform for rappelling down to the creek below the house.)

“When it’s just the two owners, they can close off the lower section and heat only their area,” says the architect, “but in the future, when the whole family is present, the lower floor can become a space for younger generations to bond.”

LED uplights throughout the house reflect warm tones from the Douglas fir ceilings, while hot-rolled steel on the fireplace and cabinets provides contrasting texture. Custom furnishings continue the rustic-and-industrial theme: Bergtraun built an extra-long dining table with a galvanized-steel top, large industrial wheels, and leftover glulam.

“The clients wanted to make this a place that was really their own,” says Bergtraun. “It’s already become a hub of activity for family and friends, and it will be for years to come.”