Black Markings On Attic Sheathing

That is a stain caused by mold mould.

Black markings on attic sheathing.

When this humid relatively warm air cannot escape the attic space before the temperature drops condensation can occur. Attic moisture and poor ventilation are the causes. If the wood is soft if it s easily imprinted when you push on it it s probably rotten. Mold on attic sheathing.

Black mold in attics. In the vast majority of cases the mold growth is caused by condensation. The variety i see most often is fuzzy green when active and goes black like that when dormant or dead. In old houses you ll usually see some spots that are stained dark or black where there was a roof leak at some point in time which was repaired but the stain remains.

Inspected a house today built in 1991. This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood. In addition to dark spots at the drywall nails and or screws in the ceiling there were also dark outlines of the ceiling joists in many areas of the house. This happens due to trapped damp air often in the late fall or early winter.

The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black. In other words you could easily see where most of the joists were located because those areas were darker than the rest of the white ceiling. When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black. The new roof doesn t help much most of the moist air is likely coming up from below.

If the dark surface of the wood smudges it could be mold. Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest. The roof had ridge vents as well as soffit vents and.