Shou Sugi Ban – Frequently Asked Questions

What is your minimum order size?

400 square feet for the first line item.

Is shou sugi ban expensive?

Shou sugi ban is actually on-par or cheaper than most stain-grade alternatives of the same grade. Kiln dried wood is often cheaper since it is made from lower grade fiber or millwork. Additionally, shou sugi ban is maintenance-optional (it never really needs to be re-oiled unless you prefer to) which makes the long-term cost-performance a no-brainer for custom homes.

What does shou sugi ban mean?

The term shou sugi ban is a Western term unknown in Japan. It is not a process, it is a product. The original Japanese term is yakisugi-ita which translates roughly to “charred cypress board”. We believe that the shou sugi ban term originates as a mis-reading of the Japanese characters for yakisugi. This product category is specifically wall and ceiling cladding made from wood and intensely burned or charred as a preservative heat treatment. The burning process combusts hemi-cellulose in the wood fibers, making the material much more resistant to moisture, UV, bugs, fungi, and fire.

What is the best wood for shou sugi ban?

We find that the best wood for shou sugi ban is Cryptomeria japonica, corroborating generations of practice. The common name is Japanese cypress, also called Japanese cedar or sugi. Cypress is straight-grained, fast-drying, flexible, tannin-rich, and strong. All desirable characteristics for siding. It has a thick, dense latewood growth ring, which burns to a more substantial, longer-lasting soot layer. Compared to other species, cypress’ chemical properties respond well to fire. It becomes incredibly dimensionally stable when milled, dried, burned and quenched by traditional protocol. All other species we find to have a handicap such as too much pitch, poor weather durability, brittle grain or paper-thin latewood.

What are the benefits of shou sugi ban?

1. It’s inexpensive. Compared to stain-grade alternatives, the long-term cost-performance when factoring in maintenance and replacement is lower than the average wood siding.

2. It’s durable. The intense heat treatment burns off cellulose in the wood so that it’s resistant to fire, fungi do not grow in it and pests do not eat it. The surface is case-hardened and there is a protective soot layer, both characteristics which cause shou sugi ban to repel water and have maximum UV protection. Shou sugi ban is suitable for nearly any climate for these reasons.

3. It’s beautiful. Wood has an undeniable natural beauty to it. Shou sugi ban can come in many different textures and colors, allowing it to match any project design. It can be re-oiled periodically to keep it looking fresh and new, or it an be allowed to weather into a unique patina as has been traditional in Japan for centuries.

4. It’s wholesome. All of our shou sugi ban comes from forests that have been carefully planted and harvested for generations. Wood siding ranks #1 for sustainability among all exterior cladding options, and 2 kilograms of carbon are captured for each 1 kilogram of lumber produced. Since the need for regular maintenance is reduced, it is less energy-intense than regular wood siding. Sustainability and healthy living are of utmost importance to us, and our shou sugi ban siding embodies those values.

Learn more about the benefits of shou sugi ban here.

What advice can you give me to help DIY yakisugi (shou sugi ban) for my project?

There is a holistic series of millwork steps for heat treatment and dimensional stability that are different from American millwork. It is not just burning lumber until it looks right or copying techniques from videos online. We have been milling yakisugi “shou sugi ban” for several decades and use logs from our own forests. There is little chance you will be able to DIY it for less cost than we sell retail for the same grade of wood.

However, if you’re dead set on doing it yourself here are the rules: Use cypress only. Face the outside of the log to the outside of the resawn moulder blank. Use shiplap or square edge, not tongue & groove. Use planks between 3/8″ and 5/8″ thick. Air-dry the wood completely, and use the traditional triangular Japanese flue method (weed burners do not work well at all.) Burn it way beyond your comfort level to where you think you’ve ruined the plank. Then, if desired, use a wire brush to knock down the soot, and finally apply an oil finish if desired.

Is yakisugi (shou sugi ban) suitable for all climates?

Shou sugi ban is time-tested in Japan, a long skinny country with climates ranging semi-tropical to Siberian. It has abrasive coastal marine weather north to south. Shou sugi ban will probably outlast any other softwood in any climate. Just make sure to install it over screen walls and with face nails, to prevent rot and minimize movement.

How does shou sugi ban weather in appearance over time?

Yakisugi, just like any natural wood siding, will patina over time. Color change can be slowed down by applying oil finishes, and the original color can be brought back in the future with a maintenance coat of oil. However, the heat treatment is originally designed to negate the need for an oil finish, and therefore the traditional aesthetic embraces a gradual patina. Unbrushed Suyaki will stay black until the soot layer erodes off in about 50 years, and then will start to change color. Gendai and Pika-Pika products will weather in color similar to any natural wood siding. All products can be re-oiled any time in future to freshen up the color and sheen as desired. There are no fast rules for how wood weathers in color since every site has different conditions. However, in general over time siding tends to mellow reddish brown on south-facing elevations and bleach to a gray tone on north-facing elevations.

Is Nakamoto Forestry’s shou sugi ban more expensive and does it have a larger carbon footprint due to being imported?

We are actually able to offer a lower price point apples to apples since we control the entire manufacturing and distribution process, and production is to economies of scale. In terms of shipping cost and carbon footprint, 99% of the trip between our coastal mills in Japan and Portland distribution facility is by efficient ocean freight–then intermodal direct to your jobsite.

Learn more about our carbon footprint & sustainability

Is shou sugi ban installed horizontally or vertically?

Both–also diagonally.

Some of the samples are cupped but will the wood be cupped when received?

Due to the traditional through and through resaw pattern optimized for wood longevity and dimensional stability, as well as the nature of how wood dries, there is often cupping of approximately 1/16″ over the board widths. Therefore, we spec two face nails every 16″ OC to keep a flat plane.

Note samples cup more than final product due to short lengths and low moisture content. Also keep in mind this is non-standard millwork and form follows function with shou sugi ban. Slight cupping is all you have to give up to achieve maximum wood longevity and dimensional stability in all other dimensions over decades of exposure without maintenance.

Can shou sugi ban be used for interior paneling?

Absolutely. There are also more stain, topcoat, and fire retardant options for interior applications.

Do you offer a shou sugi ban product for flooring or furniture?

The Japanese heat treatment process is never used for flooring or furniture. Cypress is too soft for flooring, and yakisugi planks are too thin for most furniture applications. Shou sugi ban is for wall and ceiling cladding only. Burning flooring or furniture or counters is a fun design thing we’ve seen, but it is not Japanese yakisugi “shou sugi ban” heat treatment.

What are the standard dimensions?

In Japan standard thickness is 3/8” (10mm), but we stock 9/16” (15mm) since that is as thick we can heat treat with good yield. Trying to heat treat a plank thickness over 5/8″ (example 3/4″) by the traditional Japanese charring process doesn’t work well. Interior moisture content will stay around 12% while the surface mc goes down to 0%. This results in crooking, warping, twisting, or checking. Siding and panelling needs to be straight and flat, and this is heat treatment not a cosmetic surface finish.

Why don’t you sell tongue & groove (T&G)?

T&G will wick water and rot on an exterior unless covered by a roof. Exterior wood cladding cannot be blind nailed. It will always move over time and the fasteners must be accessible to tighten the wall plane back to flat. Plus you can’t burn a thin T&G profile deeply enough to heat treat. We only stock profiles that can be used for interior and exterior, and we specialize in products that have best possible longevity.

Can Nakamoto Forestry supply custom profiles, dimensions, or clears?

We have premium select clears in our Portland stock. Our focus is to supply at a low price point and ship quickly, therefore we do not mill custom profiles or lengths.

Can North American carpenters and painters install and finish shou sugi ban without specific experience?

Yes, shou sugi ban is just like any wood in terms of installation and onsite oil finishes.

Why do you recommend prefinishing with an oil stain? Doesn’t shou sugi ban have improved longevity without oiling?

There are three reasons we apply oil finishes to our products: oil finishes bond in the soot, achieve the desired color, and make the color last longer. Some people embrace the traditional “sabi” patina aesthetic, and look forward to the organic, colorful weathering. With shou sugi ban, maintenance is optional. Re-oiling can be done as a periodic maintenance, or the patina can be enjoyed as it develops over the decades.

Can shou sugi ban be treated with flame retardant?

Yes, please inquire on your project’s specific requirements.

How is shou sugi ban installed?

Yakisugi is just solid wood lapped siding and is installed the same as untreated wood siding. See our Installation Guidelines.

What fasteners are recommended?

For exterior we recommend face-nailing with headed, ring-shank stainless nails or screws at least 1 3/4” long. Since unavailable off the shelf in a high grade, we custom order and stock black factory painted stainless nails and screws. Other nail colors such as brite, brown, white, or gray are available through your local fastener supplier. For interior applications construction adhesive and finish nails work well.

What corner or window/door detail do you recommend?

There are many many options, same as any siding or paneling, and it really is a design decision. Since we often get asked about how to do penetration, corner, screen, or other details, we developed these drawings as detail suggestions.

Does the charred finish shed from weather exposure and will it be sooty?

Most yakisugi “shou sugi ban” has an oil finish applied during manufacture that bonds soot into the wood surface so that it does not come off when touched. After installation wipe walls down with a sopping wet rag or hose them down to clean off any soot residue.

Note that since cypress has tannin content. On exterior applications there is always a chance that the tannins can bleed out from weather exposure. This can stain a light-colored underpinning below the wood siding, but after a year or so the stains will wash off.

What else should I know about yakisugi (shou sugi ban) but don’t know to ask?

Please keep in mind that yakisugi/shou sugi ban is a unique and organic wood product, with different characteristics and specifications from standard millwork. Form follows function with our product, and we have to follow rigid millwork and drying protocols for the planks to stay straight through the high temperature heat treatment process. You can learn more about what it is and how it’s made here. While our grading and millwork produces the most consistent yakisugi “shou sugi ban” product available in the world, it is still somewhat exotic, sooty, and will patina over time. Additionally, since we are often applying a dark oil to a light wood surface or a light oil to a dark wood surface, there can be a lot of variation in color tone board to board and sample to order. Make sure you are completely comfortable with the product before specifying it for your project. In the end what really matters is that you select beautiful, sustainably harvested, and natural wood siding–and not chemically treated wood or cement board.

Still have more questions?

Please contact us and one of our Nakamoto Forestry employees would be more than happy to answer any additional questions you may have about our shou sugi ban siding and other products.