What is Shou Sugi Ban?

Story at a glance:

• Shou sugi ban (traditionally known as yakisugi) is a Japanese wood preservation technique that utilizes charring and a natural oil sealant.
• Historically shou sugi ban has primarily been used for exterior cladding purposes, but recent years have seen it applied as an element of interior design.
• Aside from extending wood’s operation lifespan, shou sugi ban strengthens wood and makes it more resilient against weather, water, rot, and pests.

Yakisugi—or shou sugi ban as it’s known in the West—is a traditional Japanese wood preservation technique that utilizes controlled charring to strengthen timber.

Once an open flame has been applied to the wood, a wire brush is used lengthwise along the grain to remove any loose ash. Natural oil, such as linseed oil, is then brushed on to seal the wood.

Here we explore the history of shou sugi ban, its advantages and disadvantages, and potential applications, as well as take a look at a few examples from the field.

History of Shou Sugi Ban

Originally developed in 18th century Japan, yakisugi (焼杉)—which loosely translates to ‘to heat cedar with fire’—describes the process by which wood planks were charred as a way to make them stronger and more resilient.

Traditionally yakisugi planks were made from either cedar or cypress and were used to clad the exterior walls of homes, as they offered improved protection against the elements compared to virgin lumber.

Over time yakisugi became less and less popular as cheaper and less labor-intensive alternatives were made available. It would, however, see a resurgence in the late 1990s and early 2000s, at which point it was picked up by Westerners and marketed as shou sugi ban (焼杉板) due to incorrect pronunciation.

Today shou sugi ban can be found in and on buildings all around the world and many companies have started experimenting with charred wood. Delta Millworks, for example, offers a wide selection of shou sugi ban products in a variety of colors, textures, and grain patterns.

Why is Shou Sugi Ban in Demand?

Shou sugi ban has increased in popularity in large part thanks to its aesthetic qualities, as charred wood offers a unique appearance that simply can’t be replicated by staining. This has led to shou sugi ban being implemented indoors as well as outdoors.

“We are seeing a lot more people using heavily charred shou sugi ban for interiors, whereas in the past this was seen more as a wood for exterior cladding only,” Robbie Davis, owner and CEO of Delta Millworks, told gb&d in a previous article.

Of course, the fact that shou sugi ban is incredibly durable and greatly extends the lifespan of wood—without the use of chemical treatments—has also contributed to its renaissance.

“That thick layer of char-induced carbon protects the wood from the elements and other things that might degrade it, so you can potentially avoid any sort of oil or other type of toxic coating,” Davis previously told gb&d.

Exterior Uses

Historically, shou sugi ban was used almost exclusively for exterior wall cladding, but it has since found a plethora of additional outdoor uses, such as:

• Decking
• Fencing
• Soffits
• Siding/cladding

Interior Uses

While shou sugi ban was traditionally intended for exterior use, it has a variety of interior applications as well, including:

• Accent panels
• Flooring
• Ceilings
• Furniture

What Makes Shou Sugi Ban Sustainable?

As long as the wood used in shou sugi ban was harvested ethically—as in it’s certified by the Forest Stewardship Council (FSC) or Sustainable Green Ecosystem Council—it is considered a sustainable product. Nakamoto Forestry and Delta Millworks are two companies that source their wood from sustainably-managed forests.

Wood is, after all, a renewable material, one that absorbs and sequesters carbon throughout its natural growth period. And while it’s true that the charring process produces a small amount of CO2 emissions, shou sugi ban does not require chemical preservatives or coatings that might release toxins over time.

Shou sugi ban can also be created using recycled lumber. This helps keep waste out of landfills and reduces the need for new resource extraction, which ultimately results in fewer emissions and a lower environmental impact.

Benefits of Shou Sugi Ban

Aside from being a sustainable material, shou sugi ban offers a host of other benefits, including:

Durable & Long-Lasting

First and foremost, shou sugi ban is durable—which shouldn’t come as a surprise seeing as the technique was originally developed as a means of preservation. By lightly torching the wood, a layer of charcoal is formed across the surface, which helps harden and strengthen the timber.

Shou sugi ban also has a much longer lifespan than un-charred wood. As long as it’s properly maintained and cared for, shou sugi ban should last anywhere from 40 to 80 years.

Fire Retardant

Perhaps surprisingly, shou sugi ban is fire retardant—that is, it burns at a very slow rate.

“They’ve done burn tests on wood timbers versus steel I-beams of the same size, and the I-beams ultimately fail first,” Davis previously told gb&d. “Once you burn that timber in one inch deep, the wood physically can’t burn any further on a big solid beam, even in a raging fire that’s engulfing the building.”

This is due to the fact that the wood’s most flammable component, cellulose, has already been burned away by the charring process, leaving only charcoal on the surface. Charcoal requires extreme heat to burn, which gives occupants more time to escape should the building catch fire.

Weather, Water, & Rot Resistance

Thanks to the carbonization that happens during the charring process (and partially due to the oil applied afterwards), shou sugi ban is made resistant to weather damage, moisture-induced rotting, and even wood-eating insects like termites and wood-boring beetles.

Un-charred lumber typically requires the addition of chemical treatments to achieve these qualities.

Aesthetically Pleasing

One of the most striking aspects of shou sugi ban is its distinct appearance. Depending on the type of wood used, shou sugi ban can range in color from a very light gray to a deep black. What’s more, the charring process ensures that no two pieces look the same—a quality that adds character and lends a sense of artistry to any design that employs shou sugi ban.

Low Maintenance

Once installed shou sugi ban requires little to no maintenance whatsoever. When used outside, shou sugi ban only needs to be refinished with oil every 10 to 15 years, as is typical for most exterior wood products.

When installed indoors, shou sugi ban only requires an occasional wipe-down to ensure it remains free of dust and dirt.

Disadvantages of Shou Sugi Ban

There are, however, a few minor disadvantages to consider when it comes to shou sugi ban. However, they’re either worth it in the end or can be easily mitigated with the right know-how.

Expensive

Due to the extra labor involved in creating shou sugi ban, it typically costs more than traditional wood, leading to an overall increase in project expenses. The type of wood you use also influences the price—shou sugi ban is traditionally made from cedar, which costs more than pine or oak.

That said, this added cost is generally justified due to the increased durability and longer lifespan of shou sugi ban.

Added Risk

As is the case for any product that includes the use of fire in its manufacturing process, shou sugi ban can pose a fire-hazard during its initial creation. This can, however, be easily mitigated by leaving the actual charring procedure to experienced professionals—which is typically the case anyhow.

Examples of Shou Sugi Ban

Now that we have familiarized ourselves with the basics of shou sugi ban, let’s take a look at a few real-world examples.

Silver Rock Living Building Home

Located on Bainbridge Island, Washington and designed by McLennan Design, the Silver Rock Living Building Home is an excellent example of how shou sugi ban can be implemented sustainably.

All of the wood used for the exterior shou sugi ban siding was milled from second-growth cedar trees cut down on the project site, greatly reducing the amount of emissions produced by transportation.

“The outside of the home features charred shou sugi ban cedar siding to ensure longevity without the use of chemicals, paints, and stains,” Jason McLennan, principal at McLennan Design, previously wrote for gb&d. “The house feels natural and part of the landscape as a result of its materials and color palette.”

Other sustainable features of this green house include the use of passive solar design, rammed earth walls, FSC-certified timber, and solar panels.

Lake Lanier Private Residence

Designed by New Energy Works, this Georgia home makes heavy use of shou sugi ban as an homage to the homeowners’ love of Japan.

Employed traditionally as exterior siding, the dark shou sugi ban gives the residence a timeless flair that will only improve as the wood ages. Complemented by locally sourced real stone veneer, the charred wood siding serves to tie the home to the landscape, both in terms of material choice and color palette.

Reclaimed and sustainably-harvested walnut, white oak, larch, and Douglas fir is used throughout the home, both inside and out, to reinforce this idea of achieving natural beauty through environmentally-conscious means.

TheatreSquared

Completed in 2020 and designed by Marvel Architects, TheatreSquared is an inspiring example of sustainable theater design in action—one that also employs shou sugi ban.

Located in Fayetteville, Arkansas, TheatreSquared makes use of Delta Millworks’ Kebony Shou Sugi Ban alongside Arkansas pine in its exterior cladding. The resulting effect is a beautiful contrast, with the dark, almost black shou sugi ban complimenting the warm browns of the Arkansas pine.

While already strengthened through the charring process, TheatreSquared’s shou sugi ban cladding is made even stronger by its use of Kebony wood, an environmentally-friendly engineered wood that has improved resiliency over normal hardwoods.