Beyond the hills of Sound Avenue, where Long Island quietly fades into the North Fork, sits a 1948 Swiss chalet unlike anything else on the market — thoughtfully reimagined by its owners, both working designers, into a private wellness retreat.

Set on a 0.55-acre double lot behind mature trees and a gravel motor court, the residence offers an unusual degree of privacy across three finished levels. The chalet’s original silhouette and pitched rooflines have been preserved, while the interior has been reworked as a study in tactile, considered materials — Venetian plaster walls and ceilings, honed Carrara marble, and a hand-limewashed kitchen run throughout the main level. The great room is anchored by a sculptural Venetian plaster ceiling, and a hand-finished oxblood staircase serves as the home’s central design gesture. Wide-plank white oak floors and custom millwork carry the material language upstairs, where the primary suite opens to a private balcony framed by the chalet’s original heart-cutout balustrade.

Outdoor living was built with the same intention. A freestanding sauna, a cold plunge, and a simple wood-built temperature-controlled outdoor tub — no jets, just heat and stillness — sit tucked into the garden, alongside a wood-fired pizza oven and dining pavilion designed for entertaining. A stone patio extends the living space outdoors, framed by mature plantings that create a fully private, screened setting.

The current configuration offers 4/5 bedrooms and 2 Full 2 half baths across approximately 2,200 square feet. A third-floor guest level sits tucked beneath the chalet’s original roofline, and a lower level offers additional flexible living space.

Wander up the road to Big Rock Beach, where the North Fork does its version of a swim — quieter, rockier, and unbothered. Beyond it, the vineyards, farm stands, and harbor towns that define the North Fork are close at hand. The property is zoned for Riverhead School District.

Sale includes the attached vacant lot, offering additional flexibility for the next owner.

This is not simply a renovated house— it is a working portfolio piece for two designers, thoughtfully reimagined and ready for its next chapter. A rare category-of-one offering for a buyer seeking design pedigree.