Revamping an almost-250-year-old New England house for a modern aesthetic might seem potentially problematic, but in the hands of designer Kathleen Walsh, it turned out to be a match made in heaven. Having grown up in Massachusetts, Walsh was well-versed in the language of old houses, and thus enthusiastic, when repeat clients—a Manhattan couple with two teenage children—asked her to compose a new chapter in the Westport farmhouse they purchased as a weekend residence before deciding to relocate full time.

While the original structure dates to the late 1700s, the property had undergone a historically sensitive renovation in the early 2000s, resulting in a large addition as well as the refurbishment of a connecting barn. Better still, the infrastructure was brought completely up to date and its prize period details, including wide-plank pine floors, carved-wood fireplace surrounds and rustic ceiling beams, were beautifully preserved. With choice cosmetic tweaks rendered by general contractor Sean Desmond (a facelift for the barn’s wet bar and bathroom, the conversion of a bedroom into a built-in-bedecked office for the wife and a redesign for the breakfast nook), the stage was set for decoration.

Averse to discarding the beautiful contemporary furnishings Walsh had sourced for their Upper East Side apartment, the owners had another idea: Could she find a way to use them anew? Rather than feeling stymied, the designer instead saw the brief as an opportunity to do something unexpected. “My desire was never to make this a typical, ‘ye olde’ New England home,” she explains. “I wanted to approach this with a clear vision and having the modern furniture to work with opened the door for us to do so.”

And so, the collection made its way to Connecticut, with Walsh reconceiving, reupholstering and filling in holes with newly purchased bells and whistles. Working with a backdrop of predominantly white walls and warm wood details—a combination the wife appreciates for making “the oldness of the house pop”—the designer looked to rich hues and lively patterns for a fresh perspective. “I hadn’t worked with pine in so long, and it was really invigorating,” Walsh recalls. “It brings a natural warmth to everything, which allowed us to use color differently.” Take the guest room, where tangerine curtains and lilac upholstery spice up the quiet country ethos. In the dining room, chair backs beg a second glance with splashes of mauve-and-navy floral fabric. And the living room’s cosseting palette of mustard, aubergine and charcoal feels decidedly au courant yet appropriate for the context.

There and throughout, the designer relied on tricks of the trade to imbue a 21^st-century sensibility. “When you walk into a room with low ceilings like this, it can either feel super charming or really off,” Walsh muses. To prevent the space from achieving the latter, she employed strong vertical design elements, such as columnal drapes at the windows and linear contemporary wall sconces. “We had to create some kind of vertical rhythm to counter the horizontal lines of the beams and how low all of the furniture is,” she explains. Together these details embiggen the room while unifying the architecture with its ground-hugging Vladimir Kagan sofa, Wendell Castle coffee table and dainty barrel-backed lounge chairs.

Although the house might cater to every aspect of modern life, Walsh has interpreted it in ways that allow the family to enjoy its history. The barn, a structure dating back to the days when the property was an onion farm, has been reimagined as a lively hangout for the couple’s teenage children and their friends. And the breezeway, composed of materials salvaged from centuries-old outbuildings, now serves as an indoor-outdoor lounge in the summer and a garden room in the winter, when potted plants are brought indoors. Its French doors lead to mature gardens thoughtfully designed by landscape architect Brook Clark and which similarly mingle past with present, situating new amenities such as a hot tub and fire pit within the timeless, pastoral setting.

While the compatibility between an antique house and a contemporary lifestyle was never really doubted by the homeowners or Walsh, the union ultimately proved so successful that the designer admits to being struck by it. “Eighteenth century met 21st century, and they liked each other and got along really well,” she says. “I think it surprised all of us completely.”