This was the first level of insulation and I’d like to thank the various friends who have increased the number of empty bottles in my collection over the last few days – even my neighbour chucked a few over the fence to help out.
I started making a clay slip the day before by drying out clay on the garden path. This was then mixed with water to make a cream like consistancy mud soup.
My local timber yard supplied sawdust which I mixed into the clay slip. The bottles were bedded down on a layer of it which I then backfilled to fill gaps. This’ll provide airspaces which will trap heat for longer, and insulate it against the cold base.