Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.
Black on sheathing in attic.
Homeowner is looking for advice on how to deal with black mold on the sheathing in the attic.
This latter phenomenon occurs when the house is too humid and the warm moist air seeps into the attic where it condenses and freezes on cold attic areas.
Usually you cannot see the individual droplets unless there is an exposed area of metal or the outside temperature is especially cold.
These are commonly seen underneath roof vents plumbing stacks vent hoods.
When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black.
In the vast majority of cases the mold growth is caused by condensation.
I do not think the roofing is leaking there are gable end vents but no soffit vents they are looking to sell the house and do not want a problem with home inspector thanks.
This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate.
The insulation was contaminated and we inspected the attic side of the ceiling drywall below for signs of leak stains or mold.
The photo below illustrates where condensation comes from in an attic.
This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood.
Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green.
In an attic this is typically your roof sheathing or framing.
Roof leakage can often be seen as dark black stains concentrated and radiating out from one or more individual locations.
The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black.
The mold itself may have a cottony texture but can also be velvety leathery or.