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Why it is important to know about mold? Builders, architects and consultants - as well as home owners and building owners - need to know about mold because of potential property damage and deteriorated(lam xau di) indoor air quality from mold growth. According to one US Government agency (FEMA): Mold can damage buildings "You should be concerned about mold in your home if the contamination(Lam ban, nhiem benh) is extensive. Mold can also cause structural damage to your home. Similarly, when wood becomes soaked it can warp when it dries and cause walls to crack or become weaker." [Mold Can Damage Home and Health, FEMA Web site, http://www.fema.gov/diz01/d1379n41.shtm] Why is mold considered to be a problem now? Homes are built to control moisture through design features like overhangs, gutters and flashing. However, some modern homes, for a variety of reasons, have encountered moisture-related performance problems. One of the causes, undoubtedly, is that houses today are designed and built with more corners, angles, hips, slopes, nooks, crannies, and other design features that place greater demands on proper detailing and workmanship to keep the weather and water out. Those demands are not always met. Compounding the problem is the growing shortage of skilled construction workers. Modern energy codes may also be a contributing factor. By encouraging houses to be sealed tightly, these codes, experts point out, can exacerbate interior condensation problems, as well as indoor air quality concerns. [APA The Engineered Wood Association; "Note to Homeowners: It's the Water, Not the Wood." www.apawood.org/bbh_level_b.cfm?content=app_bbh_moisturewar] What is mold? "Molds are microscopic organisms that are present virtually everywhere in our environment. Molds break down dead organic materials, such as wood and leaves, and recycle nutrients back into the environment. All that is necessary for mold growth to start on these materials is moisture." ["Precautions during construction will save headaches later" by David Chawes, Prezant Associates; Seattle Daily Journal of Commerce online edition October 9, 2003; accessed November 19, 2003, at http://www.djc.com/news/co/11149736.html] Mold Growth In Heating Season In a heated climate, mold grows on interior surfaces. Typically, the interior surfaces of exterior walls are cool (due to heat loss), while moisture levels within the conditioned space are high. Mold growth can be controlled in two ways: (1) by preventing the interior surfaces of exterior walls and other building assemblies from becoming too cold, and (2) by limiting interior moisture levels. Adding insulation to a wall or ceiling raises the temperature of the inner surface. Controlled ventilation and control of moisture sources limit interior levels. [Home Energy Magazine online, November/December 1995] Mold Growth In Cooling Climate If exterior humid air comes in contact with the cavity side of cooled interior gypsum board, its relative humidity can rise above 70% and mold growth can occur in the cavity. Impermeable wall coverings such as vinyl wallpaper can make the problem worse by trapping moisture between the interior finish and the gypsum board. [Home Energy Magazine online, November/December 1995] Preventing mold Mold spores are always present in both indoor and outdoor air, and they can flourish in any ambient temperature from 40 F to 100 F (4 C to 38 C). But you can have some control over the moisture mold needs, and you can also have some control over the use of organic materials in construction.
["Precautions during construction will save headaches later" by David Chawes, Prezant Associates; Seattle Daily Journal of Commerce online edition October 9, 2003; accessed November 19, 2003, at http://www.djc.com/news/co/11149736.html.]
According to the National Multi-Housing Council: Ten Things You Should Know About Mold
Other resources The National Institute of Standards and Technology at Oak Ridge National Laboratory has a Building Envelopes Program (http://www.ornl.gov/roofs+walls) that addresses water vapor conditions for wall and roof assemblies. APA - The Engineered Wood Association http://www.apawood.org/bbh_level_b.cfm?content=app_bbh_moisturewar http://www.freefrommold.org/ The Federal Emergency Management Agency (FEMA) http://www.fema.gov/diz01/d1379n41.shtm The US Centers for Disease Control (CDC) http://www.cdc.gov/mold/ The American Industrial Hygiene Association http://www.aiha.org/Content/AccessInfo/consumer/factsaboutmold.htm The information contained in this document was obtained from a variety of third party sources and is cited as such. Although we believe that these sources are reliable, G-P Gypsum Corporation cannot ensure the accuracy or completeness of the information provided in this document. As such, G-P Gypsum Corporation does not assume responsibility or liability for this information. G-P Gypsum Corporation also is not responsible for installation or maintenance of its products. That responsibility lies with those involved in the actual building process. When selecting, installing and maintaining building products, issues such as local climate and geography, local building codes and performance expectations for the finished product should be take in to consideration. |
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