While I have my lunch, the PB has just arrived so an afternoon for getting some of that to the garden room awaits, I am pondering on to the next step for the garden room which is the tiling of the roof. The front elevation has, will have, 16 solar panels which covers 90% of the available space and I am wondering if I should bother tiling under the panels and if not what do I put under them to catch the water that will run off as I am not sure I want to rely on the membrane long term. The tiles are Marley Thrutone in case that makes any difference.