Using Yakisugi/Shou sugiban, Cedar sapwood?

I have a small amount of cladding to do on a straw bale house (normally plaster, I know). I have access to a source of Japanese Cedar (cryptomeria japonica) which is the timber traditionally used for yakisugi. The timber I have access to is not 100% heartwood. Most pieces, but not all, have some strips of sapwood on them. Ideally I would use 100% heart but does anyone have any experience with the durability of sapwood in these circumstances? Thanks.

Good question, I'm having trouble finding answers.

for what it's worth if you're searching in Japanese with translation tools you can use these keywords:

辺材 sapwood
心材 heartwood
焼杉板 burnt cedar boards (shosugiban)

sorry, no experience, only with charring pinus radiata stakes to put in ground to the compare how the charred and non charred versions last.

fyi great article here on why it is yakisugi not shou sugiban

https://nakamotoforestry.com/yakisugi-or-shou-sugi-ban-learn-what-you-should-call-it-and-why

Thanks for the replies. I've still not found an authoritative definitive answer.

I'm going to try to avoid sapwood if possible and a friend suggested putting a couple of sapwood boards in spots where they'll be easy to replace.

That's boards with sapwood not whole sapwood boards.

Not an answer but a question: have you sealed the straw bales in some way, before cladding?

I'm sure you know this but straw bales must be kept absolutely dry to prevent mold. Rodents may well make homes in the bales too, if they can access them. A good, thick lime render will prevent both of these things (assuming a good roof overhand for keeping off most of the rain).

pete davis wrote:sorry, no experience, only with charring pinus radiata stakes to put in ground to the compare how the charred and non charred versions last.

fyi great article here on why it is yakisugi not shou sugiban

https://nakamotoforestry.com/yakisugi-or-shou-sugi-ban-learn-what-you-should-call-it-and-why

Huh, I never looked into it, I always just assumed both were correct, since one is the kun-reading and one is the on-reading.

The Japanese wikipedia indeed only has "yakisugi" as a reading. That's usually fairly telling.

Nevertheless, it has been loaned into English as shousugiban for quite a while now, so the mispronunciation is probably not going to disappear easily.

The reverse is true in hilarious ways about lots of English in Japanese. Oh the laughs we expats have sometimes.

Luke Mitchell wrote:Not an answer but a question: have you sealed the straw bales in some way, before cladding?

I'm sure you know this but straw bales must be kept absolutely dry to prevent mold. Rodents may well make homes in the bales too, if they can access them. A good, thick lime render will prevent both of these things (assuming a good roof overhand for keeping off most of the rain).

Thanks for the tip. Yes, where the cladding is over straw bales I have done that. The cladding is also used on the north side of the house where we've gone for smaller eaves (to maximise passive solar gain). The north side is also exposed to wind driven rain and, as a consequence, we are not using straw bales on that side.