This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood.
Black on sheathing in attic.
Mold on attic sheathing.
If your attic sheathing doesn t look like new construction and is visibly black or white stained like this picture you likely have a ventilation issue that needs to be addressed and mold remediated.
I have surface mold on the sheathing in my 1982 vintage 12 6 pitched attic.
The mold is likely coming from a condensation buildup along your soffet a good trick would be to get in there and attach cut foam blocks at the top of your wall cavity up to the roof deck to seal the soffet of from the attic space wherever cooler and warmer air mix there will be condensation.
This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate.
In the attic photograph at left we show a mix of green gray and white attic mold.
Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.
The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black.
In the vast majority of cases the mold growth is caused by condensation.
Black or white staining in attic.
Mold growing on the sheathing in your attic is a serious problem that shouldn t be ignored.
While the black stains are either mould or just black dust from attic insulation settled on the.
When looking for attic mold trace both leak.
Attic mold cleaner attic mold removal how to clean attic mold how attic mold gets there in the first place and what to do to help prevent attic mold.
Why does attic mold rarely if ever affect indoor air quality in homes.
When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black.
This summer i cleaned the portion of the black stain with a dry mop as much as i could reach from the hatch opening.
The photo at page top shows white attic mold on the roof sheathing and rafters and some brown or black mold on the attic side of ceiling drywall where we pulled back insulation.
I m aware of the cause poorly vented bathroom fans and not well sealed fan fixtures lights wires etc.