the 3 layers that I am referring to was only plaster layers.
I suppose the preparation of the wall surfaces prior to the application of the 3 plaster layers could be referred to as layers but I would like to refer to them as steps, so in this regard I would like to once again qickly run through the steps prior to the application of the plaster layers---
I was referring to one type of wall construction(of which there are many-- using timberframing as the building medium)--having said that we would have in this scenario 3 or 4 cross bents of large vertical wall timbers between which would be smaller vertical studs of rough 4 by 4's
In my scenario on the exterior wall surface would be a surface of 1" square edged boards, on the interior would be also a surface of 1" square edged boarding applied to the 4 by 4 studdings, up against the side opf the large vertical timbers that make up the bents
On this surface then would be applied vertical strips of 1" by 3" at maybe 24" \oc and on these vertical strips would be the horizontal wood lath spaced so that the initial layer of plaster would be able to squeeze through and form a key on the inside cavity, it is this plaster layer that would have the hair mixture for strength