The science of drying BY TROY FEHR
Drying a structure is a science that has been developed over a number of years, but it’s only been perfected in the last ten or so years. The Institute of Inspection Cleaning and Restoration Certification (IICRC) has been promoting this science, and has accordingly developed a graduated training and certifying body that teaches this exact science to businesses and professional restorers around the globe. Approved schools teach advanced drying designations by using prop houses in their compounds and flooding them similar to real loss situations; the flooded prop houses are then dried by the students being trained (this information is further published by the IICRC in the S-500 standards). The science of drying structures takes years of training, educating, and hands-on work experience to fully comprehend and understand the knowledge to its full potential; however, once the professional restorer absorbs the knowledge, he or she then becomes an asset in any loss, large or small. The restorer will be able to attend a loss and after a short investigation, will be able to determine the appropriate drying solution, including equipment requirements and possible removals. A thorough understanding of the science of drying is essential to dry the structure within the critical time period of 72 hours. Drying within a 72-hour period will ensure microbial growth is averted, and further ensure people staying within the structure remain healthy by avoiding any exposure to mould. Mould can cause a variety of health issues for all people; however children, the elderly, and individuals with compromised immune systems are at greater risk. Due to the potential health issues, a trained professional restorer should attend all losses. When we as professional restorers attend a loss, we first take humidity and temperature readings. These readings are used to calculate specific humidity or GPP (grains of moisture per pound of air). The GPP is used as a starting point for our dry down. Losses are categorized in three ways. Category 1 is clean water; category 2 is grey water; and category 3 is black water. If this is a category 1 loss, more emphasis is put into drying the structure and less on removing hygroscopic materials. Category 2 or 3 losses will require removing some or all hygroscopic materials. Further, category 3 losses should all be tested using a swab tester or hygienic sampler, which measures the amount of present bacteria to ensure sanitization is completed efficiently.
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Ops Talk Fall 2009
LOSSES ARE FURTHER PLACED INTO 4 CLASSES: Class 1: Slow rate of evaporation - minimum moisture. Class 2: Fast rate of evaporation - some wet flooring and walls wet less than 24 inches. Class 3: The fastest rate of evaporation - ceiling, walls and insulation wet. Class 4: Specialty dry items - hardwood floors, stone, and plaster.
Regardless of the type of loss, mitigation work such as
