The first step in addressing any mold growth problem in a building is identifying and correcting moisture source(s) (see Where Does Mold Grow?). If moisture problems are not corrected, then any mold cleanup or removal that takes place will most likely be only a short-term solution; at some point the mold growth will recur. It is critical to control moisture at the beginning, during, and at the end of a mold growth removal project.

One of the most common misconceptions about mold is that it can be removed by spraying the surfaces with products such as disinfectants, biocides or cleaners. That will not take care of the problem because the allergenic and toxic properties of mold are not removed by using such products. Whether viable (living) or nonviable (dead), mold spores and other parts of the mold, when they get into the air, still present a health risk to exposed individuals.

While disinfectants and biocides may kill mold spores and take away their ability to reproduce, these products should not be used alone in addressing a mold growth problem. Either the mold must be completely removed from the affected material, or the mold-contaminated material must be completely removed from the building.

In determining which materials can be cleaned and what should be removed, the two important factors are how porous (absorbent) the material is and how extensive the mold growth is. Generally, non-porous materials (such as metals, glass and hard plastics) and semi-porous materials (wood, plaster and concrete) that are visibly moldy but structurally sound can usually be cleaned and reused. Moldy porous materials (carpeting, wallboard, ceiling tile, wallpaper, fabric, upholstered furniture, mattresses) should usually be discarded, since they absorb and hold moisture, may be internally moldy, and cannot be completely cleaned and thoroughly dried.

Cleanup and mold removal activities can expose people to mold particles and other hazards, so it is important to wear protective equipment and follow procedures safely. For complete instructions, see:

Air duct systems in buildings can also become contaminated with mold. Air duct systems can be constructed of bare sheet metal, sheet metal with exterior or interior fibrous glass insulation, or made of entirely out of fibrous glass (ductboard). If mold growth has occurred on fibrous glass or other porous surfaces, then effective cleaning will not be possible and the ductwork and/or insulation will need to be discarded. Mold growth on metal ductwork may be cleaned and disinfected following the instructions for non-porous materials. For additional details on addressing air duct cleaning see Should You Have the Air Ducts in Your Home Cleaned?, a publication of the Environmental Protection Agency (EPA).