Pre-burning the surface like this actually makes the wood more resistant to fire, a serious concern in 1700s Japan (when the technique was commonly used), as all houses then were made out of wood. But the developers of this technique also discovered that it made the wood more resistant to both rot and pests. More recently it’s been discovered that the charred wood is also UV-resistant.
As a result, a shou sugi ban finish can reportedly last for some 80 to 100 years, virtually maintenance-free. (This is not only easier on the wallet, but allows you to participate in the global trend of letting future generations worry about fixing up your stuff. Score!)
Some American firms have adopted the technique, having learned of its preserving effects, and put their own spin on it. Texas-based Delta Millworks, for instance, has applied it to far more breeds than the Japanese Cedar it was originally designed for, offering a stunning range of aesthetics. Read more here