We see ' black lines' along the roof joists and up the studs in certain parts of the house on the outside walls. What causes this... mildew... ? We are planning on painting the ceiling and walls, will paint cover these up for any appreciable length of time? We have had insulation added to the attic in the past. The soffits don't appear to be blocked and there doesn't appear to be excessive moisture in the house. Help!
These marks are caused from condensation of cold through the wood wall studs to the inside surface of the drywall. With the heat and the moisture inside the home during the cold winter months the thin layer if moisture (condensation) will collect dust particles from the heating system. Hence the black lines. Wash walls using my Shell Busey’s Home Cleaning Formula and paint with best quality acrylic latex on walls and Texture Fresh on the ceilings.