Black On Underside Of Roof

A 10 x 10 area of plywood has been removed to provide air into this area.

Black on underside of roof.

The black mold is on the first 3 truss panels. Warm wet air rises and meets the cold roof and cools. This latter phenomenon occurs when the house is too humid and the warm moist air seeps into the attic where it condenses and freezes on cold attic areas. Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.

In the vast majority of cases the mold growth is caused by condensation. Roof leakage can often be seen as dark black stains concentrated and radiating out from one or more individual locations. The mold itself may have a cottony texture but can also be velvety leathery or. Black mold growth on the underside of your roof and ceiling can be extremely common in some areas.

That excess moisture ends up as drops of condensation on the roof. This can be a problem for many homeowners and needs to be addressed as soon as it is found to avoid the consequences it can bring. The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black. Mold that grows on the underside of roof sheathing due to ideal mold growth conditions being present.

Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green. Essentially condensation occurs at night when the temperature inside a building is warmer than outside. When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black. Skips a few trusses and reappears on the next panel or two.

After several years of this there may be. Picture a cloud of moisture floating overhead between the rafters. These are commonly seen underneath roof vents plumbing stacks vent hoods. The roof has baffles at alternating thusses soffit and ridge vents.

This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood. This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate. Mold requires a few key elements in order to grow and thrive.