I've had problems with what i thought was a leaking roof, but when i had a local roofer around to quote for a repair or re-roof he informed that it was not a leak but a condensation problem i had and that the mortar like substance sprayed onto the underside of my Delabole slate clad 1950's ex-council house was the problem. I've since been told this is called "Torching", and was used by the housing authority to deal with wind blowing rain up under the tiles. This was pre-underfelt i assume?
My local roofer said that improving the ventilation was easily done with installing some slate vents and ridge tiles, but he had no idea how to remove the torching that coats the entire underside of my roof...can anyone help please?!