Black Spots On Plywood In Attic

If the dark surface of the wood smudges it could be mold.

Black spots on plywood in attic.

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. These are commonly seen underneath roof vents plumbing stacks vent hoods. 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. Black mold in attics.

Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green. Based on the reading i ve done on this site i have learned that the double stud wall system can cause condensation problems on the inside of the plywood sheathing. If you re not sure what you re looking for here s a picture of mold in an attic. After several years of this there may be.

Without proper ventilation in the attic high heat and humidity can build up which leads to moisture from a different source. In the attic the most common places to find black mold are the places where water is likely to be a problem. Walls that are improperly insulated may develop mold because they will absorb moisture from outside. When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black.

This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood. The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black. Roof leakage can often be seen as dark black stains concentrated and radiating out from one or more individual locations. It usually appears greenish black and streaky.

The black attic mold shown here confirms that this attic had a serious venting and moisture problem including moisture from sources lower in the building. The mold itself may have a cottony texture but can also be velvety leathery or. If the wood is soft if it s easily imprinted when you push on it it s probably rotten.