Could anyone tell me if it is acceptable to pin a breathable type membrane to the rafters in the loft. The problem i have is the entry of dust through the tiles as i have an old house that is closeboarded btween the tiles not felt, hence the entry of dust making going up the loft like entering a coal mine. It just seems to me to be the most practical solution as the roof is sound.
Well in my opinion it is necessary to leave a small gap in order to be certain not to interfere with eaves to eaves ventilation that should be present to conform to the requirements of Part F of the Building regulations.
Reliance on gaps between the tiles, as SB seems to be suggesting, to provide ventilation seems to me to be rather inadequate.