Hi j,
Thank you, I have to admit I've learned much from the permies forum over the years and this is my first posting!
The site was previously used for compost (many years ago) and then was given a concrete base (so we've been told by the bosses there) and then filled with sand to support potted saplings; this has since become overgrown. So unfortunately the only photos I can post will be of a very overgrown site! Although I'm in work now but will post them later
We will be clearing the site and assessing the concrete for thickness on Saturday so we'll know more then really. It's the rising damp I'm concerned about, this is our first cob structure on our own and we'd like to be able to add it to our portfolio.... hence we don't want it falling apart with damp in 4/5 years!
Sorry I haven't much more to tell you at the minute!