March 2, 2017

Wall, Baseboard Mold

Wall and baseboard mold can be a problem even if indoor relative humidity is in the preferred 50% range.
Two causes:
1. Wet materials from a water leak behind or above the wall or a wet floor or carpet. Water can hide beneath floor tile as well as wood flooring
Solution: Find the source of the water leak, fix it and replace damaged wall materials. You may use a contact (capacitive) moisture meter to locate the source of the water or moisture. Moisture meters are available for less than $50.00. A probe moisture meter will accomplish the same purpose, however it will leave small marks from the needles that are used to penetrate the surface of the material.
2. Wall cavities exist. In some cases, an unintentional airflow may deliver moist air through such interconnected cavities to the backside of the wall. This most often occurs on exterior walls. The excess moisture could have come from a sprinkler operating against the wall. It has been observed that in some construction, aluminum foil was used as insulation in exterior walls. Normal moisture that penetrates the walls is trapped behind the aluminum foil, but is allowed to pass in spots where there is an opening in the foil. As a result, very humid air will strike a small spot on the backside of the wall and cause a mold favorable condition resulting in mold growth visible inside the home, but which will be matched by about ten times as much mold on the backside of the wall where it cannot be seen, but may be smelled. Closet walls are especially susceptible to such moisture.
Solutions:
a. Manage micropressures influencing movement of air within the building’s matrix.
b. Increase the air pressure within the breathing zone
c. Increase the air circulation in the room with a ceiling fan
d. Further reduce the relative humidity by use of a portable dehumidifier
e. Use an infrared (thermal) camera or an infrared thermometer to scan temperature to see if the wall is being chilled by a cool source behind the wall. Infrared cameras are very expensive. Digital infrared thermometers are available from $20.00 up. With care, an infrared thermometer can identify a problem just as well as an infrared camera, it just takes longer to find the cold spots. During periods that air conditioners are operating, the infrared thermometer should show wall temperatures at or only very slightly below room temperature. The chilled spots will usually show more mold, so a visual inspection may be helpful. Walls may be spot chilled by air conditioning duct leaks, proximity to chiled air conditioner return freon lines or by air conditioner condensate lines which may be surprisingly cold. And, it is not unusual that an AC supply grill may be directing chilled air onto a wall instead of into the center of the room. Keep in mind that the chilled air coming out of the air conditioner register is usually very high in relative humidity. 95-98% relative humidity is more than common and should be expected. As the air warms from about 56 degrees to 76 degrees, the relative humidity will drop to around 50%.