Paul315

Thanks both for the swift replies. I'll try some anti-fungal treatment and good point on the crack. I think that before the second roofer attempted to fix it there had been a persistent channeling of rainwater in that patch. That might have given mould a foothold. That area is particularly unlikely to get much Sun too.

The white K Rend under the fascia board is discolouring brown. It is very apparent in damp conditions though the camera appears to be colour adjusting it away in the photos. It's only affecting one small part of the whole build which is under the width, rather than the length, of the black fascia board. Two roofers and two builders have looked, as have I, and we are all stumped. The tiles and felt overhang into the gutter. The roof above overhangs and keeps the area dry. There's no running water evident in a downpour. The fascia board has been sealed to the wall. Anyone got any ideas?