“Experiment” is not something you want to hear when building your house. I’m not sure what I thought when the architect told me he would like to “experiment” with the exterior siding material. But what he proposed was compelling enough to give it a shot.
The exterior siding will be shou-sugi-ban (焼杉板), or burnt sugi boards. Sugi is known as Japanese Cedar, but its really a cypress not a cedar. Instead of sugi, our sidings are western cedar. Traditional Japanese homes commonly used shousugi-ban for their external siding, although rarely used now (replaced by plastic looking siding that’s highly fire resistant). The sugi was burnt to resist rot and fire. Supposedly its harder for something already charcoaled to catch fire again.
This weekend the siding for our house was burnt. First, the surface of the cedar boards are burnt using a torch:
The result is a blackened board with a silver sheen:
Next the charcoal dust is brushed off. Some of the silver sheen remains between the grain of the wood:
The boards are washed:
Finally, the boards are oiled with oil extracted from Brazillian oiticica nut (Penofin) that acts as a sealant. Because the oil is natural, it won’t generated any toxic vapors. The result is a board that has a dynamic appearance. From different angles the board can look black, silver, or dark brown.
Like all natural wood siding materials, the siding needs to be oiled every year, spray the oil onto the siding and wipe down.
I’ve always like the look of burnt sugi used in traditional homes in Japan. You would think that a house with black siding or a black interior would be ominous or depressing. But instead these traditional homes convey refinement and are relaxing to be in. Hopefully our house will achieve the same – but because its an “experiment” the outcome is not ensured.
Update – for an a more traditional method of burning the siding, see this post