As noted in the article: The exterior walls are burned cypress, created using a [traditional Japanese technique[(https://www.houzz.com/magazine/yakisugi-ita-is-setting-the-siding-world-on-fire-stsetivw-vs~2323908): Cypress planks are heated with a blowtorch until they turn black, then buffed with a wire brush to remove the charred areas, resulting in heightened graining and a two-tone finish that’s also resistant to weathering.