I have a disused stable and am looking to make it usable as a hobby workshop / garden studio.
my question is about the best way to insulate. It's only a hobby area and hence doesn't have to be to any great standard, nevertheless I would like it to retain some warmth and be usable during the winter months.
Specifically, the wooden framed walls have 8'x4' sheets of 15mm plywood very securely nailed all around to a height of 4'. I was wondering whether it would be OK to drill holes in the top of these and fill the frame gaps below with some sort of granular insulation - as I would like to keep the plywood walls and removing them first to fit rigid insulation will damage the ply. My concern is that I have been advised to fit a vapour barrier to stop the building 'sweating' and I couldn't do this with infilled granular products.
Above 4' the frame is exposed so I would uses celotex or similar and board over.
Any advice appreciated