Designed by Bohlin Cywinski Jackson (BCJ), Seattle, this 2,100-square-foot project shares the simple planning, modulated structure and refined aesthetic of the California Case Study Houses: a program of experimental prototypes sponsored by Arts & Architecture Magazine from 1945 to 1962 that brought modern design to the masses. The difference in the new Northwest houses is an emphasis on compactness, wood construction and the region's changeable light.

Wood stair treads slip through the space between maple slats and rest on them for support.

The owners came to BCJ looking to reinvent the way they live. After 20 years in a commodious 1908 Craftsman-style house in Madrona, they wanted to downsize when the last of their three children left home.

"We want our kids to feel welcome but not move back in," laughs the husband, a retired computer executive now collecting specimen plants for London's Royal Botanical Kew Gardens. The wife is a volunteer chaplain at a local hospital. The solution: a one-bedroom house with his and her offices that double as guestrooms.

The house is a narrow bar running the length of a steep corner site. The long north and short east sides face the street. The design creates a variety of spatial experiences by collecting four levels under an overriding metal roof. The large roof slopes up as the site plunges 16 feet down to 25th Avenue East.

At the upper end of the site, off an alley, the roof covers a concrete walkway to the front door and a gravel carport.

Horizontal and vertical wood members slip by each other at joints in the architect-designed kitchen cabinets, hutch and dining table.

Polycarbonate glazing ("polygal," the plastic window-wall material used in greenhouses) brings light into the airy outdoor space while providing privacy.

The main entry is mid-level into the house. Immediately to the left is a convenient alcove for sorting mail and her office with its own private deck. A flight of stairs leads down to the main living level and into a wide corridor along the southern edge of the house. It culminates in an outdoor deck overlooking the Arboretum, Lake Washington and the Cascades.

"The design is the progression from the front door to the view, just as architecture is the process of getting from here to there," explains architect Peter Bohlin.

A line of steel columns differentiates the main hall from rooms along the north side of the house - kitchen, dining room and living room. Steel columns and beams extend outside to carry the wooden floor joists of the deck. Throughout the house, materials slip past each other and structure projects beyond corners, increasing the sense of spaciousness by drawing the eye beyond edges and boundaries.

The front door is off the airy carport screened by translucent panels on the right. The overriding roof covers a series of inside levels oriented to the view.

The most dramatic space is a double-height living room open to the master bedroom above. Red hardie panels (a fiber-cement siding) on the upper portion of the wall emphasize the vertical space. An 18-foot ladder of windows turns the corner, dissolving the boundary between interior and exterior. Since the living room floats 10 feet above the ground, the column of windows parallels the mid-section of a 50-foot cedar, creating the sense of a perch in the tree.

On the north wall, the fireplace mantel is a pair of steel plates that appear to float over maple/apple plywood panels. The hearth is a simple step up in the polished concrete floor. Radiant heating in the slab keeps it toasty while eliminating the problem of placing mechanical ducts in an open space.

A low wall with a hutch on one side and counters on the other separates the kitchen and dining room. The maple kitchen cabinets are individual boxes that slip into a grid of wood brackets bolted to the wall's exposed studs. The dining-table top is a piece of oriented-strand board, a plywood usually used for structural sheathing but transformed by a clear resin finish into a surface as lush and variegated as marble.

Steel columns draw a line between the bedroom and a sitting/exercise area opening to an upper deck.

Upstairs, a free-standing cabinet separates the master bath from the bedroom. One side houses the sink, with a washer/dryer hidden behind a sliding door. Maple paneling on the other side doubles as a headboard for the platform bed designed by BCJ. Underneath, large drawers roll out for storage.

On the lowest level of the house are another full bath and office opening to the yard. Boiler and storage areas tuck into a large space under the entry level above. Even though the couple dispersed a large portion of their possessions among family, friends and charities, BCJ provided abundant storage by slipping it into nooks and crannies. "The hardest part of the entire project was getting rid of our accumulation of stuff," one of the homeowners says.

Throughout the house the wood framing and steel structure are exposed, adding richness without ornamentation to the spare design. "We are interested in revealing the nature of things and the way places are made," explains Bohlin.

Replacing ubiquitous drywall in many places are hardie panels, maple slats or sheets of polygal laid lightly on top of the framing for a glimpse of the underlying studs. A fine grid of exposed metal fasteners adds another level of detail. Replacing the opaque with the translucent allows light inside in unexpected ways. In her office, high polygal panels above a built-in closet draw filtered south light from the main hallway into the 10-foot-high space.

"There's a continual sense of discovery - and so many great places to sit and read," she says.

Of course, exposing the wood framing creates more challenges for the general contractor. Every piece of lumber was hand-selected for visual defects, then sanded before installation. During construction the project was tarped to keep the wood from becoming stained, and afterward wood was sealed with a coat of clear lacquer.

"It's really a piece of fine furniture," Eric Thorsen of Seattle's Thorsen Construction says of the house.

The stair connecting the main living level and the master bedroom is a prime example of the closer-than-normal construction tolerances required by the design. A partial wall of evenly spaced maple planks separates the two runs of steps and forms the guard rail. The wood treads slip through the spaces between slats and rest on them for support. There is no way to hide mistakes in this type of detailing - no trim or drywall to cover imperfections.

The same exacting details transform the modest exterior materials. A fine grid of exposed metal fasteners bolts hardie panels and polygal panels onto the structure, articulating the straightforward form. Exposed metal flashing between panels creates horizontal bands that give scale to the long north and south facades. Blocks of panels painted red, blue and yellow animate the exterior and emphasize its kit-of-parts quality.

The home in many ways embodies directions Northwest design has been moving for two decades: It is compact and simple, uses modest materials and is wholly modern without being austere.

Though spare, it welcomes more layers of personalization. "The design is clearly considered not overly demanding; rigorous and spirited, yet light," says Bohlin. The front door was handmade by friends the couple made while he was cataloging plants in Africa. Likewise, their sculpture and paintings tell a story of connections and journeys. In many ways, the modulated interior is the perfect foil to the couple's funky folk-art collection. By reveling in the way buildings are made, the house reveals the nature of people, time and place.

Sheri Olson is a Seattle-based contributing editor to Architectural Record.