Mold on your window sill is usually indicative of excessive moisture issues within the structure. Given proper temperature (most commonly 68-86 degrees), substrate (porous carbon based matter/wallboard) and moisture (60% relative humidity) mold can begin to grow. Mold can grow on a substrate as minute as biofilm (very thin layer of organic matter/ex. dust). Relative humidity tells us how “wet” or “dry” the air is. As air is warmed, it expands and its relative humidity decreases, because warmer air can hold more moisture. Conversely, as air is cooled, it shrinks and its relative humidity increases. Cool surfaces reduce the temperature of nearby air. If air is cooled enough that its humidity reaches 100 percent, condensation occurs. Mold growth usually occurs on surfaces that remain wet or damp for prolonged periods of time.

So, keep an eye out for “sweaty” windows and the mold growth that may occur therein. Also, it should be said, installing dual pane or insulate windows will only differ your moisture issues. Call us, it may be easier than you think.