A quaint riverfront retreat in Virginia’s Northern Neck is both exactly—and not at all—as it appears. First-time visitors will note thoughtfully placed windows flanking the front door, a weathered-shingle hipped roof and clapboard siding in a sage color designed to merge with its surroundings. The impression is of a well-maintained, century-old cottage.

However, that’s only part of the story. The Montross dwelling was actually built in the 1980s as an easy and affordable shared getaway for Judy and Dusty, a couple who live in Arlington and originally shared the property with a friend. The trio had found the perfect lot with Potomac River views after vacationing in Westmoreland County, Virginia, and Judy and Dusty decided to put skills they’d previously developed flipping houses to good use by building their own.

The duo—Dusty was a teacher and Judy worked in publishing—conceived a Cape/Colonial hybrid with simple lines and 2,600 square feet spread over three stories. “We wanted to give a nod to history,” Judy says, noting the nearby birthplaces of George Washington and James Monroe.

The modest façade masks three full levels, with the lower floor built into the hillside behind the house. The main floor encompasses the kitchen, half-bath, sitting and dining rooms and rear deck. Four bedrooms are divided equally between the upper and lower floors; each pair of bedrooms enjoys a river view and a shared hall bath.

With construction completed, Judy focused on the interiors, keeping budget and practicality at the fore. “We didn’t want a fussy house where you couldn’t sit down with a wet bathing suit,” she explains.

Her scavenger-hunt approach yielded items found during past renovation projects and at nearby vintage shops. She clad the walls in rough-hewn exterior siding, painted in Shell White by Sherwin-Williams. White oak flooring is the perfect backdrop for jute, sisal and woven rugs, easily moved for cleaning. Oversized windows dressed in pleated shades let in the view. Pops of color come from accent pillows, bright rugs and cuttings from Judy’s flower garden. Furnishings rarely change, she says, except for the upholstered pieces “because they do take a beating.”

Eventually, Dusty earned his contractor’s license while Judy left her job and began taking design courses. An internship introduced her to designer Melanie Whittington, who became a close friend and—after Whittington launched her own firm and hired Judy—a colleague for 10 years. When Whittington and her husband purchased their own Northern Neck property, the designers began consulting each other. “We always collaborate on our houses down there,” Whittington says.

With help from her friend, Judy (who has since retired) continued to develop the cottage’s collected aesthetic. “The house is a mix of old and new with lovely greenery and a balance of found objects with things that are modern and sleek,” Whittington relates. “It always looks fresh.”

The mix is evident in the foyer, where an antique cabinet and table share space with bamboo chairs from Kenian Fine Rattan Furniture. The dining room features a vintage cabinet and farmhouse table surrounded by mid-century-style chairs—plastic for practicality.

Found objects abound. One of the upstairs bedrooms showcases a headboard Judy fashioned out of foraged wood, while a stack of vintage suitcases serves as a de facto table. Another bedroom has a modern metal bed frame with stools that double as seating and storage. Every bedroom, in fact, is a quasi-public space. “Judy and Dusty rotate rooms,” says Whittington. “There’s no room that’s theirs.”

Thanks to its thoughtful floor plan, the house has never needed an addition or renovation, though the kitchen has been updated with new Ikea cabinets and bright chartreuse walls. Seat cushions, rugs and pillows are replaced as they become worn from regular use. “The house is loaned out all the time to friends; there’s always somebody coming and going,” Whittington explains. “There are dogs running in and out and wet feet. It’s a well-used house. Nothing is fragile.”

But there are surprises. The figure of a woman about to dive perched atop a coffee table. A floor lamp with a base of ship’s rope. A metal pig in the foyer welcoming guests. An antique iron bench in a bathroom. “In your own home, you get to choose things that make you happy,” Judy observes. “This is a house where you don’t have to take things too seriously.”

Interior Design: Melanie Whittington, Whittington Design Studio, McLean, Virginia. Styling: Charlotte Safavi.