Last April 2012 we had Cavity wall and loft insulation to our three bedroomed terraced house. Although we have most windows open in the house we have noticed a black/dark line 2 or 3 inches from the ceiling in every room including down the hallway and stairs. This appears to be getting darker. We did not have this prior to the installation. We are thinking maybe it could be some type of mould appearing but would like further advice please. There is about 6" of insulation in our loft space and it appears to be dry although no vents were installed in the loft area or in the walls.
My husband has been diagnosed with another respiratory infection and I have had symptoms too so am wondering if there could be a connection with the loft/wall insulation and these black lines appearing.
We would really appreciate some advice.