In this photo of very dark mold in an attic in a wet attic mold which we found to be brown in the microscope looked black on the plywood.
Attic plywood wet.
Some woods are much more resistant to rot and fungal attacks.
Inner plywood of roof wet.
Attic insulation combination of fiberglass covered by cellulose.
Wet sheathing was found in attic area due to lack of venting.
The attic vents provide a secondary method to help everything.
2 layers of shingles.
If the sheathing either boards plywood or composite board along the lower edge of the roof is soaked and you can see a corresponding accumulation of ice on top of the roof ice damming is occurring.
Plywood is original 49 years old.
It s not a vapor barrier.
The second variable is the species of wood used in the plywood.
Even if conditions are conducive to mold growth elevated moisture plywood made from a fungal resistant wood will resist mold growth for quite a while.
Quite often the roof flashing is defective and needs replacement.
Attic venting attic moisture and ice dams.
The black attic mold shown here confirms that this attic had a serious venting and moisture problem including moisture from sources lower in the building.
What to do about a wet attic.
As i m sure you know building codes require this type of attic to be vented.
Wanted to add more cellulose but installer said it would make wet roof worse.
Black mold in attics.