Indescribable Warmth: Underfloor Heating at Frank Lloyd Wright Smith House

Stepping into the Smith House on a grim and wintry day, one is instantly enveloped in warmth. The warm tones of brick and tidewater cypress walls, and the soft, textured furnishings help to create a cozy atmosphere, but the real effect is felt through radiant heat rising from the pigmented concrete floors.

Red concrete floors dominate this view of the Smith House Living Room, circa 1959. Melvyn Maxwell and Sara Evelyn Smith Papers, Courtesy of Cranbrook Archives.

Underfloor heating was a frequent feature of Frank Lloyd Wright’s Usonian houses. Concerned with elegant and efficient use of space, these modest buildings for middle-income families utilized radiant heating set into the concrete slab flooring. Warm floors prevented heat transfer from bodies to cold buildings and allowed the air to be kept at a cooler temperature than conventional radiator-heated homes. 

A worker rakes gravel over underfloor heating pipes during Smith House construction, 1949. Melvyn Maxwell and Sara Evelyn Smith Papers, Courtesy of Cranbrook Archives.

Frank Lloyd Wright’s ideas about underfloor heating were adapted from the principles of the Korean heating system called ondol, literally ‘warm stone,’ that he encountered during his time in Japan. While working on the Imperial Hotel project, Wright was invited to visit the Tokyo residence of Baron Okura Kihachiro. After dinner in a freezing cold dining room, the party was invited for coffee in the Baron’s heated “Korean Room.” In his 1943 autobiography, Wright described the shift in temperature in rapturous terms: 

The climate seemed to have changed. No, it wasn’t the coffee; it was Spring. We were soon warm and happy again – kneeling there on the floor, an indescribable warmth. No heating was visible nor was it felt directly as such. It was really a matter of not heating at all but an affair of climate. 

Frank Lloyd Wright, 1943

Wright was instantly taken with this “indescribable warmth” and immediately specified electric heating in the Imperial Hotel bathrooms. On returning to the United States, he continued to explore the use of heating systems in both residential and commercial projects.

His first private home to incorporate underfloor heating was the Herbert Jacobs House, in Madison, Wisconsin, completed in 1937. The Jacobs House would become a model for Wright’s Usonian houses and an inspiration to architects and homeowners worldwide. By the time that Melvyn and Sara Smith began construction of Smith House in 1949, developers like William Levitt were popularizing the use of radiant heating in tract housing developments across the United States. 

Frank Lloyd Wright, Plot Plan and Heating Plan for Mr. and Mrs. Melvyn M. Smith, 1949. Melvyn Maxwell and Sara Evelyn Smith Papers, Courtesy of Cranbrook Archives.

The Smiths employed engineer Clarence Toonder to help implement the heating plan designed by Frank Lloyd Wright’s office. Blueprints show the copper tubing as it snakes through the L-shaped floor plan of Smith House, ensuring that every room would be warm and comfortable. 

Clarence L. Toonder, Invoice for engineering services, September 26, 1949. Melvyn Maxwell and Sara Evelyn Smith Papers, Courtesy of Cranbrook Archives.
Taylor Supply Company to Mr. Melvyn Smith c/o Revere Copper & Brass Inc., Memorandum of Goods, October 20, 1949. Melvyn Maxwell and Sara Evelyn Smith Papers, Courtesy of Cranbrook Archives.
Revere Copper and Brass Incorporated, Radiant Panel Heating: A Non-Technical Discussion, 2nd ed., 1949. Melvyn Maxwell and Sara Evelyn Smith Papers, Courtesy of Cranbrook Archives.

Documents in Cranbrook Archives reveal that Melvyn and Sara Smith chose to use Revere Copper and Brass Incorporated to supply their heating system. The Smiths may have selected the company for its historic pedigree. North America’s first copper rolling mill was established by founding father Paul Revere in 1801, and the company is still in operation today as Revere Copper Products. Or perhaps they were persuaded by a booklet issued by Revere Copper and Brass on the subject of “Radiant Panel Heating” which incorporated informational texts and convincing illustrations.

Newly digitized images of the construction of Smith House show the Revere Copper pipes laid out, while workers rake gravel and smooth concrete pigmented with Wright’s signature red coloration.

The result was an expanse of red concrete that flows from room-to-room, uninterrupted by thresholds or unnecessary doorways. In the summer these floors, polished to a leather-like shine over the years, stays cool to the touch. In winter, as copper pipes continue to warm the whole house from below, one can imagine how Frank Lloyd Wright felt in Baron Okura’s Korean Room. The effect is amplified by long built-in benches and custom furniture and tables that keep you close to the heated ground. Though Smith House’s underfloor heating system has received many updates over the last 72 years, it is still functioning as intended, keeping the house cozy with its “indescribable warmth.”

—Nina Blomfield, The Decorative Arts Trust Marie Zimmermann Collections Fellow for Cranbrook Center for Collections and Research, 2021-2023

Editor’s Note: Interested in learning more about Nina’s research on the Smith House and its collection? Sign up to hear her presentation, “Little Gems: Studio Craft at Cranbrook’s Frank Lloyd Wright Smith House,” at The Decorative Arts Trust Emerging Scholars Colloquium, January 22, 2023, virtual and in-person at the Park Avenue Armory, New York City. 

Registration is also open for Curator Kevin Adkisson’s History of American Architecture: Frank Lloyd Wright lecture series. Weekly lectures begin February 14, 2023, and are presented virtually and in-person at Cranbrook Art Museum de Salle Auditorium. 

4 thoughts on “Indescribable Warmth: Underfloor Heating at Frank Lloyd Wright Smith House

  1. I grew up in a 1947 house in Huntington Woods, Michigan, that was loosely based on one of Wright’s L-shaped Usonian home designs. We had radiant heat in the bathroom floors (wonderful after a shower) and in ceilings through the rest of the house. Our “basement” was the home’s second floor, as the furnace and radiant system was designed to be powered from above. One drawback was that radiant heat is bone-dry. Without forced-air humidification, houseplants shriveled quickly. The pipes in the ceiling often banged at night as they expanded and contracted, which convinced me that we had dinosaurs living above us. The house even had (gasp) an electric garage door with a button inside our car. Kids in the neighborhood would come over so we could run it up and down from the driveway to entertain them.


    • Thanks for sharing these wonderful memories, Douglas. I wonder if the Smiths had the same problem with their houseplants, because all the greenery in the house is of the plastic, “permanent botanical” variety! The Smith House heating system also makes an occasional squeaky bird-like noise that is a little disconcerting for a first-time visitor. But it’s all worth it for these toasty warm floors.
      – Nina


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Create a website or blog at

%d bloggers like this: