If you go outside on a humid day you may inhale 100,000 mold spores. If you place five bags of mulch around bushes, you inhale another 1,000,000 mold spores and you never once complain about mold. However, when the mold inspector tells you have 1,000 mold spores of Penicillium in your basement you start to have short-term memory loss, headaches, and your fingernails turn green.
Homes today are tight and built with materials that no longer hold water. So when they get wet, they stay wet. In the old non-air-conditioning days, homes could dry from the inside out and the outside in.
Today we install exterior siding systems such as EIFS synthetic stucco, Cultured Stone, Hardy Board siding without proper drainage spaces (which could be simply a 3/8 drainage gap behind the siding material) or without proper drainage planes (which could be simply properly installed house wrap), and some builders even install brick without weep holes which are needed to drain brick when it becomes wet.
Additionally, we now have aluminum-clad windows, which are now rotting all over the country and we fill the interior of our walls with foam, fiberglass, or cellulose. Some of us even install non-breathable plastic Visqueen or vinyl wallpaper on the inside of our walls. Then, we turn on our unbalanced HVAC system along with man’s dumbest invention the furnace humidifier and then we wonder why we have mold.
Mold need spores, nutrients and water. Spores and nutrient are everywhere. Mold can grow on a dusty mirror, it eats drywall for dessert, and yes, it grows on your green board drywall in your bathroom. You can not fool the mold. We can not control mold spores or nutrients, but we can control water. No water, no mold, end of story.
Water comes from water events, house dampness, moisture intrusion, moist air entering the home due to negative pressures from your poorly balanced HVAC system, high indoor humidity from moisture generators such as a basement sump pump that does not have a 100% sealed lid, humidifiers, vented crawl spaces, ventless appliances, leaking gutters, all of which promote mold growth, badly installed roof insulation.
Along with the mold, are bacteria, dust mites, cockroaches, other insects, and chemical out-gassing of building materials Therefore, we have multiple agents present in damp homes that simultaneously can cause health effects. Furthermore, damp homes permit Pre-1978 painted surfaces to fail and become lead dust, pipe insulation to become heavy, fall to the ground, and become friable possibly containing asbestos or fiberglass. We have OSB, particleboard, and pressed wood all of which can out gas formaldehydes when they become moist.
For more on this subject check out – The Truth About Mold – Its Effect on You and Your Home – Part 2