Hello After being quoted £18k a couple of years ago to retile my roof I have decided to do it myself. I have done loads of research and I'm pretty sure I know what to do although I'm also very aware of the potential of giving myself problems in years to come if I don't get it right. It's a 'T' shaped bungalow with a pretty large footprint so has 4 valleys and 4 gable ends. I'm in Scotland so I plan to use 11mm OSB as sarking then membrane and a smooth concrete tile. I just have a couple of questions that I can't seem to find answers to on the internet. Battens: since I'm using 11mm OSB as sarking and won't have gaps between them, should I use counter battens? I'm thinking any water that gets between the tiles will get trapped by the horizontal battens if I don't use vertical ones. How often are the battens nailed, I obviously don't want to make any more holes in the membrane than I really have to. Do I just use galvanised nails, do people ever use stainless steel nails? Would there be any benefit in using copper nails? Membrane/felt: What kind of membrane would anyone recommend? I don't mind spending a little more for good quality since I'm saving money doing it myself but I have also read people saying felt is better than modern equivalents. My roof currently has asbestos looking small plates under the overhanging tiles on the gable ends. I plan on using plastic dry verges. Do I just tuck the membrane under the OSB and nail it underneath cutting it back close to the brickwork which would be hidden with the dry verge? If this is the case, should I buy and measure the dry verge first to ensure I don't overhang my OSB sarking by too much which would leave visible membrane from below. Where the membrane meets the gutters, is this left a couple of inches longer than the OSB rather than folded back and nailed from below and hidden by the guttering. The membranes tend to be bright colours like green or blue and anything left on show is going to stand out. Thanks in advance for any replies, I really appreciate the input from anyone with expertise in this area.