I'm in the process of taking out the garage door and replacing with timber frame clad on outside and double glazed window. I wil batten the walls with dpm between the breezeblock wall and the battens and then put in rockwool/earth wool before using osb or ply but am stuck as to what to do with the roof?!? It's corrugated metal with ventilation down one side. How do I insulate it and stop condensation. I live in Oban wet and cold winters. All help advice greatly appreciated. I have attached a photo. Cheers