Mold and fungal spores occur naturally outdoors, where fungi are the earth’s most important recyclers. Indoors, mold needs moisture to grow; it becomes a problem only where there is water damage, elevated and prolonged humidity, or dampness. Common sources of excessive indoor moisture that can lead to mold problems include:
- flooding from surface waters (i.e., overflowing rivers) or from severe storms;
- roof leaks from damaged or missing roofing materials, ice dams or blocked gutters;
- storm-driven rain through window frames, exterior walls or door assemblies;
- leaking pipes, sewer back-ups or overflows;
- damp basements or crawl spaces due to a high water table or poorly managed rainwater drainage; and
- condensation on cold surfaces.