from Marty in Green Bay, WI:
#243
Why do I get mold in my house in the corners and on the window and would getting new windows stop that?
New windows are only a temporary fix, this is a moisture problem.
Molds are part of the natural environment. Outdoors, they break down dead organic matter like leaves and dead trees. That’s a good thing for many reasons, but indoor mold growth should be avoided. Molds reproduce by means of tiny spores, invisible to the naked eye and float through outdoor and indoor air. Mold may begin growing indoors when mold spores land on surfaces that are damp or wet. While there are many types of mold, none of them will grow without water or moisture. It is impossible to get rid of all molds and mold spores indoors, but it is possible to prevent or control mold growth by controlling moisture indoors. If there is mold growth in your home, you must clean up the mold and fix the water problem. If you clean up the mold, but don’t fix the water problem, then, most likely, the mold problem will come back.
Moisture in the form of (liquid) condensation is common in homes that suffer from high relative humidity (how moist the air is) conditions. Even homes that have moderate relative humidity can experience condensation problems when the weather gets very cold. Often, there are surfaces like windows, walls, and ceilings that are cold enough to be at or below the dew point temperature causing the water in the air (in vapor state), to condense (become liquid) on these cold surfaces. The interior relative humidity can be affected upward by a myriad of things ranging from bulk water leaking into the home from outdoors (i.e. roof leaks, around windows and doors, foundations and/or landscaping around foundations), plumbing leaks inside the home, to the production of moisture generated by the lifestyle of the occupants. The simple, everyday activities like cooking, bathing, and washing clothes all add to the moisture load. Even an individual at rest will release close to a quart of water per day.
Indoor air temperature settings also have an impact on relative humidity. The lower the air temperature, the less capacity that air has to hold moisture in a vapor state causing the relative humidity to increase. As air temperatures rise or fall, so do surface temperatures. It is important to keep all surfaces above the dew point temperature to avoid condensation on those surfaces as a practical means to avoid molds that need that water or moisture to grow and proliferate.
Installing new windows might be enough to prevent condensation on the windows due to an increase in the windows thermal performance as compared to the old windows, but the cost of replacement windows can be extremely high when compared to controlling the indoor environment. Often, an appropriately sized and well installed (quiet) exhaust ventilation fan can be used to control indoor relative humidity. The added benefit is controlled, fresh air for the occupants.
Engaging the services of a professional energy consultant through the Home Performance with ENERGY STAR Program is great way to help you determine a practical plan of action based on the results of a homeowner interview, scientific testing, and a visual evaluation. Because the consultant is not trying to sell you new windows (or anything else), the advice is unbiased and reliable.
For further information regarding mold in your home, visit the EPA’s "A Brief Guide to Mold, Moisture, and Your Home."
Published Monday, June 08, 2009