Water or drip marks scattered on the attic floor.
Wet sheathing in attic.
In the vast majority of cases the mold growth is caused by condensation.
Moist or wet insulation.
There are many signs that an attic is wet.
Moisture or frost on the roofs sheathing.
Buckled or damaged roof sheathing.
The osb and in fact any wood panels must be allowed to dry completely depending on how wet the panels are this could be a few days before any roofing material is applied to avoid trapping moisture under the roof material that could cause edge swell and buckling.
It is never a good idea to install a roof over wet plywood or any type of roof sheathing.
Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.
Installation tips osb roof sheathing the ol sage builder trubord.
These signs can vary contingent on the catalyst of the problem and are generally worse on north facing or shady sides of roofs.
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.
Prolonged wetness will rot out the roof sheathing.
Often this is first noticed when re shingling.
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.
Wet sheathing was found in attic area due to lack of venting.
How does condensation get in the attic.
This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate.
Mold on attic sheathing.