Not wet but some areas slightly damp.
Attic plywood wet.
The second variable is the species of wood used in the plywood.
Quite often the roof flashing is defective and needs replacement.
Some woods are much more resistant to rot and fungal attacks.
Wet sheathing was found in attic area due to lack of venting.
Attic venting attic moisture and ice dams.
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.
Attic insulation combination of fiberglass covered by cellulose.
It s not a vapor barrier.
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.
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.
What to do about a wet attic.
As i m sure you know building codes require this type of attic to be vented.
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.
Black mold in attics.
Plywood is original 49 years old.
Wanted to add more cellulose but installer said it would make wet roof worse.
If any moisture makes its way to the plywood the damp plywood will dry out on hot sunny days.