Roof Sheathing Mold

Attic spaces are one of the most common places in a home for mold to be found growing.

Roof sheathing mold.

In the vast majority of cases the mold growth is caused by condensation. A close examination of the photo above reveals large amounts of mold on the underside of the roof sheathing. Generally tearing off a roof and roof sheathing and perhaps roof framing to remove mold would not be sensible nor cost justified. What caused the mold and why did it thrive in this attic space.

This phenomenon occurs in vented attics and is more common in new homes than old homes. Mold growth provided it is not just cosmetic mold which can simply be left alone can be cleaned from wood surfaces by blasting scrubbing or even simple surface wiping depending on the surface accessibility and smoothness. The presence of mold in your attic is often the result of poor ventilation insufficient insulation moisture from a roof leak or improper venting from your bathrooms or kitchen. The insulation was improperly installed over the soffit vents blocking air from entering the attic.

Mold on the underside of roof sheathing is also very common. One puzzling aspect of the phenomenon is that the mold is found in well built homes that comply with all relevant building codes. Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest. Because wood is porous it may be difficult to remove the mold stains from sheathing but you can kill the mold by cleaning the sheathing with bleach and water.

Increasingly homeowners in the pacific northwest are noticing mold on the underside of their roof sheathing.