In the vast majority of cases the mold growth is caused by condensation.
Roof boards damp.
Look for damp spots on the underside of your roof.
This leads to the formation of damp spots on the surface of the roof.
It is never a good idea to install a roof over wet plywood or any type of roof sheathing.
Another leading cause of condensation in roofs is the use of wood burner cookers.
Such cookers often allow for the quick rise of moist air leaving behind the cold air.
Also look for a thin stream of water flowing down one of the rafters.
Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.
This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate.
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.
Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the.
Roof cuts and thermographic imaging can also detect moisture in addition to other strategies.
Cracking noises can sometimes be heard when walking on the roof during wintertime as a thin layer of ice breaks he adds.
Follow the water uphill till the wood is no longer wet.