This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate.
Wet sheathing in attic.
These signs can vary contingent on the catalyst of the problem and are generally worse on north facing or shady sides of roofs.
In the vast majority of cases the mold growth is caused by condensation.
Prolonged wetness will rot out the roof sheathing.
Moisture or frost on the roofs sheathing.
If you have ceiling leaks only in the spring it may be that ice has been forming on the sheathing all winter and it suddenly melts when a warm spell arrives.
Moist or wet insulation.
Mold on attic sheathing.
Water leaks are more obvious as telltale signs such as darkened water stains evidence of mold on the ceiling inside the house or wet sheathing.
What to do about a wet attic.
Installation tips osb roof sheathing the ol sage builder trubord.
Water or drip marks scattered on the attic floor.
Attics can suffer two types of leaks.
There are many signs that an attic is wet.
Wet sheathing was found in attic area due to lack of venting.
Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.
Buckled or damaged roof sheathing.
Often this is first noticed when re shingling.
It is never a good idea to install a roof over wet plywood or any type of roof sheathing.