Cob: alternatives for pressure treated wood

[Darel Henman]

Comments below:

Kerry S Tebbetts wrote:
> Of all the suggestions for cob hybrids, I like the cob house wrapped with
> exterior strawbale the best.  
I might not be necessary, I think the cob should be enough.  You can
always add later and only if necessary.  I'm talking of a real cob wall
and not light clay here.

> Also, I don't really think that any high mass material is necessary on
> the North, east and west walls.
Why do you think this?  The mass would be good there and work especially
well if it were insulated.

> So, it would seem that a pole frame would
> be a better solution, with light clay infill used where I want the
> insulation and cob used where I want the mass.
You're basically talking a timbre frame house.  Then yes light clay
would be easy to fill in.  I'd still make it a thick wall through.

How do you know how much mass is enough?   Did you do calculations or
modeling to derive this?  

> 
> As I understand it, pressure treated lumber is recommended for a p&b, but
> I really don't like the idea of using wood treated with arsenic.
I haven't heard this.  Simple strong timbers should work.

> Is there a homemade recipe for treating wood?
For interior wood, paint it with fermented persimmon juice.  You might
have to make it.
There are other ways as well, like using borax or lime and something.

> Also, is there a way to use stones
> for the pole footings rather than concrete?
I'm not sure you'd pass inspection with this.   Stones mortared together
could work.

> My reasoning is that the
> stone footings would keep moisture from being wicked up to the wood, the
> same way that a cob's stone foundation does.
That what the building regulations say.

> 
> I read a thread in the archives about the possibility of using cob to
> form the posts for a post and beam frame?  Would this work?
No.  You'd not get load bearing beams and posts out of cob.

You could think of a wattle and daub type structure if you were in a
hurry.  These walls can be thickened as years go by provided a keying to
the next layer is possible.

> Has anyone
> tried it with any kind of success?
> 
> shae

Darel