Am I being over-zealous or simply paranoid?
I intend to have my loft boarded out entirely. The roof is well ventilated, and will stay that way. There is fibre insulation to the depth of the ceiling joists and the boarding would lay direct on the joists. This is a 100mm depth (they are short spans and there will be only very light storage). What precautions should be taken to avoid trapping water-vapour beneath the boarding? It is intended to use moisure-resistant chipboard.
Should I vapour-check the ceilings of the rooms beneath - in which case is there a vapour-check paint that can be overpainted with emulsion? Or should I ensure gaps between the boards? Or am I over-reacting?
Your views would be greatly appreciated.