We're looking at natural building alternatives and I considered cordwood, but even if we found land with a lot of trees to cut down, seasoning the wood for three years isn't really feasible.
But where I live people are always selling cheaply, or even giving away, timber pile offcuts from house foundations. They're round and the right size.
Any thoughts? Obviously they're treated, which would make them more rot-resistant but less natural (but then, we would completely enclose them in plaster/cob/whatever anyway, as we don't like the exposed ends look).
Who said you need to let logs sit for three years to build cordwood? Not a rule I've ever heard ;) "Obviously they're treated" - that's not just a matter of more or less "natural" that's a question of exactly what are they treated with and how toxic is it? And then you might want to consider how much of that toxic material you want to surround your living space with. Encasing it within a natural, breathing plaster is not isolating any toxic material the piles were treated with from your living area. Concrete wouldn't reliably contain it either.
Kris Harbour has an entire series of videos about his roundhouse build. Here's one part addressing the cordwood walls
I read the three-years rule on some article about cordwood building, but you're right - since then I've found people saying you only need to leave it for a year, and a few even saying less time than that.
The offcuts would be treated for in-ground use, so I assume it'd be pretty hardcore preservatives. Good point about the earthen plaster not containing any toxins.
Probably a bad idea, then. A shame - it seems like a very readily available waste resource.
The issue about treated timber is a complex matter that few actually study.
Over the years various methods of treatment have been used and some are shocking, but not all.
If you burn any treated timber and eat the ash you may be ill.
In 2021, treatments are varied to suit the final use of the timber, thus different levels of the treatments [ toxins] are used.
Most house frames are treated timber so the level of toxins is lower, in those than the level used for timber going into the ground..
Dangerous Fumes do not come out of treated timber, otherwise the whole world would need to demolish all new timber framed homes.
Accordingly I would study the timber you are offered and see if you can use it.
Its my guess you can if its treated for use as above ground external use timber.
I have to say, John, having read the article you linked, I have a very different take-away than yours appears to be. Conventional house construction framing is not using pressure treated lumber, so your assertion there is pretty badly off target. Normal dimensional construction grade lumber is kiln dried, but that's the limit of "treatment" it gets.
I urge people to read the article John linked and to reach your own conclusions regarding the message it contains.
I don't know enough about this topic, so I'm locking it with a staff reminder that discussion of toxic ick like Pressure Treated wood belongs in the cider press.
Something to consider while the staff review this thread, the OP mentions "treated"... surely there are many ways of treating wood. People have been building with wood for a little while prior to pressure treating tech.