~andy, I don't really want to buy more loglap to put over the outside to make it look like a log cabin again (seems silly to cover it up and then pay extra to make it look like it did before you covered it up in the first place...!!) so will probably go for insulating on the inside and losing some room inside. Will probably batten horizontally (air gap) then put Celotex insulation against this and then sheets of ply 12mm thick.