What Is the Black Stuff on the Basement Ceiling That's Spreading?

Source of the Growth

• The main culprit for black growth on a basement ceiling is mold. The moisture content in the basement, as well as water from the structure above due to plumbing leaks and condensation on water lines, will reach the basement ceiling. Humidity is also introduced by any plumbing fixtures or appliances that are installed in the basement, such as washing machines, bathroom fixtures and water heaters. This moist environment is conducive to mold growth.

Toxic Black Mold

• According to the Centers for Disease Control (CDC), black mold itself is not toxic. The toxins produced by the release of mold spores (mycotoxins) by certain types of mold make the fungus toxigenic, or capable of producing toxins by its biological processes. The type of black mold that poses the most serious health threat is Stachybotrys chartarum. This fungus will grow anywhere condensation or high humidity is present. Although this mold is actually more of a greenish-black color, it is the type often called "black mold." The CDC does not confirm a proven link between black mold and serious health problems although information on its website does state that the Institute of Medicine found in 2004 "sufficient evidence" to link mold exposure with upper respiratory infections.

Non-Toxic Black Molds

• The good news is that many types of black mold that can appear on a basement ceiling are non-toxic. The most common types of black mold that invade humid areas are Cladosporium and Aspergillus, fungal organisms that are found both indoors and out. The effects of these molds, as well as other non-toxic black molds that may appear on a bathroom ceiling (Ulocladium, Stemphylium, Pithomyces, Alternaria, Dresclera and Aureobasidium), pose no serious health hazard. However, prolonged exposure to any type of fungus, whether toxic or not, presents the possibility of an increase in allergy and asthma symptoms.

What You Can Do

• The best way to address black stuff growing on a basement ceiling is to remove the affected materials and replace them. Many basement ceiling consist of manufactured ceiling tiles, such as metal-framed "drop ceilings," and these tiles are readily available and easy to replace. Repair sheetrock (drywall) ceilings by removing all mold-infested areas. Removing the humidity is important, too. Use de-humidifiers in the basement or open basement windows, if possible, in warm months. Install insulation in finished walls and use padding under carpeting on concrete floors.