Moisture Control

 

To diagnose or prevent a moisture problem, keep in mind four key elements of moisture behavior in buildings:

1.      Typical symptoms of moisture problems.

 They include corrosion of metals, the growth of surface mold or wood-decaying molds, insect infestations, spalling exterior brick or concrete, peeling paint, failing floor adhesives, stained finishes and health symptoms.

2. Sources of moisture.

Among them are rainwater, surface water, ground water, plumbing water, indoor and outdoor sources of humidity and sewer water.

2.      Transport mechanisms.

They include liquid water leaking through holes, wicking through porous materials, or running along the top or bottom of building assemblies and water vapor carried by warm, humid air leaking through assemblies and by diffusion through vapor-permeable materials.

3.      Common failures of moisture control elements and systems.

Moisture controls include site drainage, gutter systems, above- and below-grade drainage planes, effective flashing, condensate drainage and humidity controls. Failures can occur during any phase of a building’s life and may include poor site selection or design, poor material or equipment selection, improper installation or sequence of building materials and equipment, insufficient coordination between trades during construction and insufficient or improper maintenance of materials or equipment.

 

Health Implications of Dampness in Buildings

At the request of the U.S. Centers for Disease Control and Prevention (CDC), the Institute of Medicine (IOM) of the National Academy of Sciences convened a committee of experts to conduct a comprehensive review of the scientific literature concerning the relationship between damp or moldy indoor environments and the appearance of adverse health effects in exposed populations. Based on their review, the members of the Committee on Damp Indoor

Spaces and Health concluded that the epidemiologic evidence shows an association between exposure to damp indoor environments and adverse health effects, including:

Ø   Upper respiratory (nasal and throat) symptoms.

Ø   Cough.

Ø   Wheeze.

Ø   Asthma symptoms in sensitized persons with asthma.

 The committee also determined that there is limited or suggestive evidence of an association between exposure to damp indoor environments and:

Ø   Dyspnea (shortness of breath).

Ø   Lower respiratory illness in otherwise healthy children.

Ø   Asthma development.

 Details of the results of this review were published in a 2004 report, Damp Indoor Spaces and Health.

It is also important to note that immuno-compromised individuals, such as some categories of hospital patients, are at increased risk for fungal colonization and opportunistic infections. After the publication of the IOM report, a study by Lawrence Berkeley National Laboratory concluded that building dampness and mold raise the risk of a variety of respiratory and asthma-related health effects by 30 to 50 percent.

A companion study by EPA and Berkeley Lab estimated that 4.6 million cases of asthma, 21 percent of the 21.8 million cases of asthma in the U.S. at that time, could be attributed to exposure to dampness and mold in homes