Mold in a Home
Mold has become a big concern in recent years. Mold is the subject of lawsuits, a terror to builders, subject matter for front-page writers, the reason for school closings, and the growth of a "new" industry – mold testing and remediation. With all this talk about mold, you might think it is new. You might think it is a complex issue. Mold is not a new nor a complex issue.
Why is mold here in the first place? Mold has a purpose which is to breakdown and eat dead organic matter. Without mold, dead plant and animal material would grow and pile up. Molds purpose - if it's organic, dead, and wet, mold will eat it. Organic means it is a material that was once living, such as wood and paper. Mold sends out its spores everywhere and they can lay dormant for many years.
Since mold spores are everywhere, and our building materials and contents of our homes (furniture, boxes, clothes, etc.) are made from organic materials, this factor cannot be controlled. The only factor that we can control in our homes is the moisture.
Mold needs 70% Relative Humidity (RH) or more to grow; however this is a loose number. Some molds can grow at less RH. In many cases, like in a crawl space, the RH of the surrounding air, and the RH of the surfaces are two different things because of temperature differences between air and surfaces.
Mold will usually not be able to grow in normal ventelated or conditioned environments. Mold usually needs to have a additional water source such as a plumbing leak or rain water entering the house through the roof or siding.
Mold likes processed organic fibers best. In other words it will grow on paper and cardboard first. Paper is like "mold candy" and the exterior of sheatrock and fiberglass batts are paper. After that it will grow on fiberboard and chipboard, and then plywood, and finally on framing lumber.
Mold releases airborne spores or "seeds", which are so light they float on the slightest air currents, off to find more suitable places to grow. Most people are not allergic to mold spores but the higher the concentration of mold spores, the greater percentage of people who will be bothered by them.