Black Spots On Plywood In Attic

Black stains in attic.

Black spots on plywood in attic.

It s probably just darkness that comes from the wood being repeatedly wetted and dried from frost forming melting and drying. Attic moisture and poor ventilation are the causes. 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. In the attic the most common places to find black mold are the places where water is likely to be a problem.

When the attic has been damp or wet there might be a more serious problem with aspergillus sp. 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. After several years of this there may be. 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.

Frost can also form on plywood in certain cases. Walls that are improperly insulated may develop mold because they will absorb moisture from outside. You have something growing on the surface of the wood caused by excess moisture. Black mold in attics.

Nails collect frost when the weather conditions and rh are right. In this photo of very dark mold in an attic in a wet attic mold which we found to be brown in the microscope looked black on the plywood. Without proper ventilation in the attic high heat and humidity can build up which leads to moisture from a different source. Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green.

Last winter i took a look into the attic and noticed black stains and water marks. I did some investigating this august and sure enough i noticed a few black mold spots on the inside of the plywood. The new roof doesn t help much most of the moist air is likely coming up from below. If the wood is solid it s probably fine.

Call it microbial mildew or mold it really doesn t matter. That is a stain caused by mold mould. If the dark surface of the wood smudges it could be mold. The variety i see most often is fuzzy green when active and goes black like that when dormant or dead.

If the wood is soft if it s easily imprinted when you push on it it s probably rotten.