Basic Cob Question

[Michael Saunby]

On 06 November 1998 20:23, Jim Puglia [SMTP:avele at primenet.com] wrote:
> Howdy all.  Quick question.  I am considering cob for building my home
> (strawbale is my other option at the moment) and was wondering how well
> cob holds a screw.?
>

Cob construction doesn't use screws.

Though if you're wanting to put screws into wall to fix shelves, etc. then 
rather than those nasty plastic things that some people use to fix screws 
into masonry then a lump of wood would be the right thing.

I've been doing a bit a replastering in my cob house, and have found that 
an area of plaster that had been renewed by a previous owner using a 
conventional gypsum plaster just peeled away, it had never really bonded to 
the cob.  On the other hand, the much softer earth plaster which remains in 
other parts of the house seems fine.  Maybe the new plaster had been 
applied to dry cob, or this is just a troublesome area (by an external door 
frame) I don't know.  Anyway I've used haired lime plaster this time, but 
even with the damp weather we've been having and wetting the wall first the 
plaster still dried out faster than I would have liked, with quite a lot of 
cracking.

I'm tempted to try using earth plaster for an internal wall that needs 
repairing.  The existing plaster seems to be made up of earth (yellow 
clay), cow hair (red) and hay. I've saved some of this old plaster so I'll 
wet it to get an idea of how it drys out and what it's like to work with 
before I try mixing up some fresh stuff.  I may add some lime to it since 
lime putty is easy to get hold of here.  I suppose I could check the pH to 
see if the old stuff had any lime added.


Michael Saunby