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Heat, wood, stone, steam—the sauna’s appeal lies in its elemental simplicity. Yet beneath that minimalist façade lies a surprisingly complex design challenge that has architects and homeowners rethinking how to integrate wellness spaces into contemporary living. The expanding home sauna market, projected by Kohler Co. to reach $4.6 billion globally by 2033, reflects more than just a trend toward self-care; it signals a fundamental shift in how we conceive of domestic luxury. AD PRO spoke with architects and designers across the country to distill best practices.
Siting the sauna
In the States, saunas have often been relegated to basements or tucked away within primary bathrooms. Yet positioning them in more central spaces can encourage daily use, justify the investment, and elevate the experience. At Yun Architecture, principals Susan Yun and Felix Ade recently installed a sauna on the ground level of a Brooklyn passive house, opening directly onto the garden. “It allows access to nature to become part of the routine, and the sauna to become a place to socialize,” Yun explains.
Others suggest functional adjacency. “Pair it with a fitness room, a cold plunge, a hot tub, maybe a steam room,” says Todd Kennedy of CCY Architects. “Because saunas now tend to be more compact, they fit into a ritual: workout, stretch, sauna, shower, relax.”
“The sauna coupled with the cold plunge in a home spa or gym is definitely in,” agrees Michael Altneu, Vice President of Global Luxury at Coldwell Banker. “It’s part of the demand for wellness amenities, especially post-COVID.”
Getting the build right
Installation requires more than a good location. “You need to have a certain amount of insulation in the walls, ceiling, and floor, and a vapor barrier inside the insulation facing the room,” says Ade. “These keep the heat inside and allow for a quick preparation time.”
Consider, too, the interior architecture. “The height of the sauna is very important in terms of where your body is relative to the hottest pockets of air,” says Of Possible founder Vincent Appel. Saunas traditionally have low ceilings and raised platforms, with tiered benching, so that users can pick their distance from rising hot air. “Think about the direction of the heat coming out of the sauna stove, and the position of vents behind you on the platform, which will come together to achieve the best experience.”
Beyond the box itself, architects recommend designing the threshold—including the changes in lighting, flooring, or acoustics—to signify the transition into a ritual space. Traditional low doors, requiring users to step over a sill, “make you more aware of your body and relationship to the building,” says Appel.
Scale and comfort
Sizing is both a practical and cultural consideration. Saunas can be as small as a one-person closet conversion or as expansive as a social hub. But bigger isn’t always better. “The larger the sauna, the harder it is to heat evenly and maintain,” Ade explains.
Vertical clearances also matter. “You usually need six to twelve inches above the sauna for installation,” says Philipp von Dalwig of vonDalwig Architecture. “That can be a constraint, especially in apartments or condos.”
In terms of overall size, Ade recommends a minimum of about seven and a half square feet for a two- or three-person sauna. Von Dalwig, meanwhile, suggests about double that, recommending that designers base it on the client’s needs, including the number of users, bench layout, and available space.
Heat source, heat style
The heating element defines both performance and user experience. Leading industry names include Harvia, a Finnish company celebrating its 75th anniversary this year, which offers traditional, infrared, and steam options in over 100 countries. Estonia’s Huum offers cutting-edge iterations of ancient wood-burning (or more modern electric) sauna stove technology, controlled by phone apps. “Every manufacturer has its own rules about matching heater size to sauna volume,” Kennedy notes. “Coordinate early so you don’t end up with underpowered or oversized equipment.”
For interior builds, electric heaters are the most popular: They are lightweight, require no chimney, and often bypass insurance or inspection issues. Wood-burning stoves, though less common in US residential projects, carry traditional appeal.
No matter the heat source, the idea is to heat the sauna stones until they radiate heat, which can also be released as steam when doused with water. “A sauna ranges from about 165 to 220 degrees, with about 10% to 20% humidity,” says Appel. “When you pour water on the rocks, that humidity level spikes to 40% or 50%. That change of feeling in the dew point of the atmosphere on your skin is kind of euphoric, an elation.” Among the many stone options, he recommends peridotite igneous rock, which has excellent heat retention, resists thermal stress, and won’t off-gas.
The right wood—and use of glass
Wood is the primary expressive surface—but not all are created equal. While cedar is classic, designers are increasingly playing with aspen, hemlock, and thermally modified woods, each with its own distinct hues, scents, and maintenance profiles. “We usually suggest hemlock or cedar,” says Appel. “Hemlock provides a clean, modern look with excellent heat retention and stability, while cedar offers a warm, aromatic experience with natural resistance to moisture and decay.”
Yun often uses alder and aspen, the latter recommended by their Finnish—who better?—millworker. “In general, we prefer woods that do not secrete resins or do get too hot,” says Ade. She also likes the pale hue of those woods, which balances out the usually dark interiors of most saunas.
Glass walls and large windows are increasingly popular, lending light and a sense of modernity. For the sauna she installed in Brooklyn bordering a garden, Yun designed a triple-glazed window to provide views of the greenery: “It creates a visual connection to nature,” says the architect.
Prefab and plug-in options
Not every client has the budget for bespoke. Prefabricated saunas have become more stylish and turnkey. Kohler recently introduced its first line of saunas, which come in three sizes with a choice of two exteriors, can stand alone or be integrated into the walls of a renovation project. A five-person model costs about $19,000.
Von Dalwig recently installed a two-person prefabricated infrared sauna from Sunlighten, a popular sauna manufacturer based in Kansas, on a Brooklyn rooftop extension. The unit, which cost approximately $4,500, “came flat-packed and slotted in seamlessly.” says von Dalwig. “It’s electric, user-friendly, and doesn’t need hours of preheating.”
In the end, the sauna is not just a hot box but a ritual space. And the more it feels like a destination, the more likely clients are to integrate it into daily life. “There’s something special about stepping out of one domestic space and into a sauna,” says Appel. “Using a sauna should feel ceremonial.”
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