Look for damp spots on the underside of your roof.
Roof boards damp.
Roof cuts and thermographic imaging can also detect moisture in addition to other strategies.
Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.
Also look for a thin stream of water flowing down one of the rafters.
Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the.
In the vast majority of cases the mold growth is caused by condensation.
When this warm air reaches the spaces in the roofs it gets in contact with cold air and condenses.
Look for potential entry points like roof vents valleys loose nails and mark the area with chalk so you can examine the exterior of your roof after it quits raining.
Such cookers often allow for the quick rise of moist air leaving behind the cold air.
It is never a good idea to install a roof over wet plywood or any type of roof sheathing.
This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate.
Another leading cause of condensation in roofs is the use of wood burner cookers.
Follow the water uphill till the wood is no longer wet.
This leads to the formation of damp spots on the surface of the roof.