Sun streams through a round aperture in the vaulted ceiling. As the day deepens, a beam of light meanders along a curved upper wall, marking the passage of time, then vanishing.

Lofty enough to grace a museum or temple, this feat of engineering can be found in the heart of a new custom home in Bethesda. “It gives you a Pantheon effect,” observes architect David Mogensen of McInturff Architects. “And reminds you that we’re rotating.”

More surprises unfold beyond the 4,685-square-foot, modern dwelling’s restrained façade. It all started when the new owners asked Mark McInturff and Mogensen to assess the property and a dated Cape Cod once on site. The architects initially developed two schemes: one to renovate the existing structure and another to imagine a new one. “By the time we made the old house look right, it would have cost more than a new one,” says McInturff.

Starting with a clean slate, the team took a studied, creative approach. Their plan not only dovetails with the site but also with their clients’ vision and lifestyle. Both doctors, the owners were leaving behind a townhouse and dreamed of open, free-flowing spaces with large, unobstructed windows forging a strong connection to nature and the sky.

McInturff gauged that the lot could accommodate three generous spaces from side to side. Distilling the center-hall Colonial oeuvre, he situated two outer volumes with a void in between. “That axis became the entry and dining space,” he notes. The living room and an open staircase were placed to the left of the entry and the kitchen and a study to the right. The primary suite resides above the kitchen; two guest suites await across the divide. A lower level houses a gym, media room and mechanicals.

“We call it the Split House because everything supports the split, from front to back,” McInturff says. “The rear yard is like a private outdoor room, which allowed us to blow out the back.”

While the formal, symmetrical street side dressed in gray brick nods to buttoned-up Bethesda, the glassy rear elevation channels Palm Springs. Sliding doors along the kitchen, dining and living areas give way to an ipe terrace spanning the back of the home. “The back is more idiosyncratic,” remarks Mogensen. “Things kind of pop out of the volumes and it’s more open.” On one side, the primary suite protrudes above the main roofline while on the other, a guest suite hovers over the terrace.

The owners tapped landscape architects Lila Fendrick and Douglas Stookey to elevate the lackluster, quarter-acre property and its run-down pool. They remedied grading issues and bordered the garden with show-stopping foliage, from ‘Vanessa’ Persian Parrotia that softens the front façade to Green Giant Arborvitae rimming the back. “Our goal was to provide beautiful views of trees from all the windows,” says Fendrick. “We wanted to make the garden feel like a private green oasis.”

Crisp geometry and spare, simple lines define the airy interiors. In the double-height entry, a steel-and-white-oak bridge connects upper spaces sheathed in curved, white walls. “When you stand there and look outside, it’s magical, especially when it snows,” marvels the wife. Luceplan pendants made of laser-cut plywood hover like works of art above the dining area. Lower, 10-foot ceilings delineate the living room with its double-sided fireplace and the sleek kitchen and breakfast nook.

From “invisible” painted-steel closet pulls that mimic molding to electronics storage hidden in the fireplace wall, clever design moves abound. Take, for example, the floating, steel-and-white-oak staircase enclosed in glass. Illuminated by full-height windows, Mogensen’s meticulous creation exposes all of its parts, becoming a sculpture in its own right.

Then there is the dining room’s oculus. “We made a physical model, and then a 3D-computer model oriented to the sun, the time of the day and the month of the year,” details McInturff. “That was incredibly valuable to us and to the clients, in terms of planning and understanding the outcome.”

Throughout the design phase, the architects, builder Justin Barrows of Added Dimensions, landscape pros and the owners deliberated over every complexity to arrive at this airy refuge that, in the end, appears deceptively simple. Summing up the process, McInturff quotes Mario Campi, a Swiss architect he’s long admired: “Campi once said, ‘A good house is a simple plan—with exquisite detail.’”

Architecture: Mark McInturff, FAIA, McInturff Architects, Bethesda, Maryland. Kitchen Design: Amir Farazad, Poggenpohl, Chevy Chase, Maryland. Landscape Architecture: Lila Fendrick; Douglas Stookey, Lila Fendrick Landscape Architects, Chevy Chase, Maryland. Builder: Sam Morgan; Justin Barrows, Added Dimensions, Takoma Park, Maryland.

RESOURCES

THROUGHOUT
Windows: weathershield.com. Paint: Super White by benjaminmoore.com. Staircase Fabrication: Metal Specialties; 301-421-1832. Lighting Design: hinsondesign.com. Audio/Visual & Security: mediacraftav.com.
REAR EXTERIOR
Dining Table: troscandesign.com. Chandelier: luceplan.com. Fireplace: sparkfires.com.
LIVING AREA
Sofa: ligne-roset.com. Living Room Rug & White Chairs: mgbw.com. Ottoman: urbancountrydesigns.com. Coffee Table: persianogallery.com.
KITCHEN
Cabinets: poggenpohl.com. Countertops: caesarstoneus.com. Cooktop & Ovens: gaggenau.com through poggenpohl.com. Faucet: dornbracht.com through poggenpohl.com. Bar Stools: cb2.com.
BEDROOM
Bed & Rug: mgbw.com.