Shou Sugi Ban: Charred Wood for Dramatic Exteriors and Interiors

On a snowboarding adventure in Japan, Matt and Steffanie Musich wandered around Tokyo when they noticed a small structure. A temple perhaps. Or a teahouse. It was made of wood. In the right light, its blackened exterior appeared to glisten with an array of gray hues that, at times, flashed with iridescence. The Musichs were beguiled. 

After returning to their home near Lake Nokomis in Minneapolis, they began working on a project: a new garage with room for a micro-brewery, workshop, and bicycle storage, with a native prairie garden, apiary, and sauna on top. When they asked their architect, Jody McGuire, a principal at SALA Architects, about what they'd seen in Japan, McGuire immediately knew what they were talking about. Yakisugi (焼杉), referred to in the West as shou sugi ban, a Japanese method of charring wood dating back to the 1700s. 

When the Musichs asked McGuire if they could use shou sugi ban siding on their sauna, the answer was a resounding yes.

Shou Sugi Ban Is Chemical Free, Easier on the Planet

Traditionally, shou sugi ban is performed on cedar - sugi is the Japanese word for cedar. The process of shou sugi ban, done by hand, involves several steps. First, the wood is blackened or charred using fire. Then, it is cooled, and any soot or burnt debris is brushed off the surface. The boards are then finished with oil. Fire is often considered a destructive force when it comes to wood. Interestingly, it's the damage done during the charring process that makes shou sugi ban a sound and sustainable choice for buildings. 

Here's why. The charring process works at the cellular level, creating a carbon layer on the wood's surface. The char protects the interior wood like a stain or sealant. Shou sugi ban thus enhances wood's durability. It's a natural way to preserve wood without chemicals, paints, or other surface treatments. The carbonized wood is also waterproof. 

There's more, adds Jonathan Orpin, founder, and owner of Pioneer Millworks, a reclaimed and sustainable wood products company that also produces shou sugi ban. "In addition to putting a protective coating on the wood to minimize UV degradation," Orpin says, charring protects against insects, bacteria, and mold. "Functionally, shou sugi ban chars their dinner. We burn the front and back of our boards for these reasons." Here's a video on Pioneer Millworks' shou sugi ban process. 

Aside from the gas used during the charring process, shou sugi ban is environmentally friendly. There are few to zero chemicals present in the process and the resulting product. Moreover, shou sugi ban is wood, adds Orpin. "Is there any renewable resource with a lower carbon footprint than wood? Or with a higher embodied carbon? Wood rocks!" 

Charmed by Char

For the Musichs, "Both the look of shou sugi ban and the artisanal ethic of the process suited the project and the clients," McGuire says.

"They were up for doing much of the finish carpentry work themselves and for putting in the elbow grease to get long-lasting results," she adds. "There's something fun about the exterior of the sauna (traditionally a building heated by burning wood) having a charred exterior. And, let's be honest: Who doesn't like playing with fire?" 

Over several weekends, with help from numerous friends, the Musichs placed hundreds of 1 x 6 cedar boards milled into a shiplap profile on concrete blocks. (You can also use metal sawhorses, McGuire suggests.) 

Using a propane-fueled weed burner, they made two passes along each plank—just to the point at which they'd achieved alligator-scale-like texture. The couple then used a brush with hard bristles to remove the ash. They finished the boards with tung oil, "which is a little bit processed, but not as toxic as many other substances," McGuire says. Here's a video of the Musichs at work.

The 10-by-12 sauna used about 350 square feet of shou sugi ban siding, McGuire adds. "In a world of over-processed products with lots of toxic mystery ingredients, shou sugi ban is a straightforward solution," McGuire says. 

"People, especially do-it-yourselfers, take comfort in that," she continues. "For many reasons, shou sugi ban remains popular in Japan—because it adds fire, rot and insect resistance to wood, and has the ability to weather beautifully. Those reasons, combined with its DIY opportunities and sustainability aspects, make shou sugi ban an option full of potential, particularly for cabins and outbuildings." 

Aesthetic Impact of Shou Sugi Ban

Architects around the globe have been cladding houses—their own and their clients'—in shou sugi ban for several years. Because, in large part, of the striking aesthetic a black-clad home imparts. In a 2017 New York Times article, writer Amanda Fortini waxed poetic about a house designed by the New Haven, Connecticut firm Gray Organschi Architecture with Aaron Schiller, founder of the New York City-based Schiller Projects. 

The home, she writes, is clad using about 80 charred louvers that were burned by hand. She comments that the color looks both modern and ancient and is reminiscent of obsidian. Fortini also notes that the color is striking and that it seems to visibly shift, based on the weather and time of day. The house was clad in shou sugi ban. 

"It makes a stunning visual statement, with its depth of color and textured surface," says Orpin. His company, Pioneer Millworks, produces shou sugi ban in three finishes: deep char, color char, and shallow char. The company uses western larch, not cedar. He says that this is "because cedar is overharvested. Instead, we're using an underutilized species that does just as good a job as cedar, if not better." 

Where to Find Shou Sugi Ban

Delta Millworks in Austin, Texas, and reSAWN TIMBER co. in Telford, Pennsylvania, also sell ready-made shou sugi ban siding for interiors and exteriors, as well as for floors and decks. On its website, reSAWN cites the benefits of shou sugi ban, from wood's low embodied energy, natural insulating properties, and carbon sink to shou sugi ban's durability and "unmatched aesthetic." 

"The modernizing of shou sugi ban," according to reSAWN, "allows us to make products featuring many color tones that fit with virtually any project aesthetic." reSAWN says that the grain structure and natural markings of the wood add to its beauty. They can take advantage of the variations in texture and tone to add to the wood's rustic appeal. reSAWN's products and designs have been used across the country, from Silicon Valley offices to Pennsylvania homes. 

Architect Katherine Hillbrand, also a principal at SALA Architects, has incorporated shou sugi ban into projects, as well, including on a sculptural home on a hillside outside of Stillwater. Delta Millworks supplied the shou sugi ban for the house. Says McGuire: "For the right client, it can be the right look and the right application. It's also easy to understand this process. That's attractive. People who love wood, love fire, and are looking for a sustainable option, fall in love with shou sugi ban. When people love it, they take care of it, and that's part of sustainability too." 

Article by:

Camille LeFevre

Camille LeFevre is an architecture and design writer based in the Twin Cities.