Product
Moisture, Mould, Mildew and
Maintenance
Construction Practices
Repairing Water-Damaged
Building Systems
What should you do if your wallboard has mould and mildew on it? This document discusses the conditions neces-
sary for mould and mildew growth and provides basic repair steps. You鈥檒l also find additional information to assist
you in understanding mould and mildew.
Conditions Necessary for Mould and mildew are microorganisms that can, under the right conditions, find a suitable environment in which to
Mould and Mildew Growth grow and survive on building materials. The best way to address mould and mildew is to make sure that building
materials do not get wet before installation and are not exposed to moisture inside the finished building.
When building materials get wet, mould and mildew may grow. Condensation, pipe leakage, roof and window leak-
age, and incidental splashing can cause building materials to become wet. Water combined with other conditions
such as temperature, humidity, shade or darkness, and oxygen supply helps the development of mould and mildew.
In all situations, immediately identify and address the source of water to prevent re-occurrence of the problem.
Repair Use caution when evaluating and repairing water-damaged building systems. Do not investigate or begin repairs
unless you are qualified to do so and understand the potential risks involved. Where mould growth is extensive,
a qualified independent construction professional should assess your specific situation and help develop and
implement a plan that addresses each of the following:
鈥? Eliminating the conditions for mould and mildew growth
鈥? Cleaning mould and mildew from surface of material(s)
鈥? Removing damaged material that cannot be cleaned
Elimination of Conditions: Focus your efforts on removing the conditions that cause mildew growth. In the cases of leaking roofs, ceilings,
Keep It Clean, Keep It Dry! walls, or plumbing problems, repair the source of the water immediately. In a flood situation, follow the American Red
Cross and FEMA (Federal Emergency Management Agency) guidelines for the safe return to affected areas.1
Once you eliminate the conditions for mould and mildew growth, the cleaning, repair, or removal begins.
Cleaning or Removal: This is a very complex question, and proper investigation and research on your part is critical. This document
Which is best for you? provides a small portion of the information necessary to evaluate your situation along with additional reference
information.
Cleaning Clean It, Dry It, Disinfect It
If cleaning the surface of the materials is your decision, proper scrubbing removes surface mould and mildew.
Once conditions for mould and mildew growth have been removed, the following procedure is suggested to
remove mould growth and staining:
鈥? Use appropriate protective equipment
鈥? Mix detergent and potable water in a clean container
鈥? Use detergent, bleach and potable water for stubborn stains (follow manufacturer鈥檚 instructions for use of cleaning
supplies; never mix bleach and ammonia); provide adequate ventilation with use of bleach
鈥? Scrub areas that exhibit growth and staining
鈥? Rinse with water鈥攎ake sure you don鈥檛 soak the gypsum board while cleaning and rinsing
鈥? Allow gypsum board to dry and inspect for visible growth and staining
鈥? Repeat as necessary until affected areas are clean
Removal A Project Specific Decision
Proper cleaning addresses the surface of the gypsum board. However, when construction materials get wet, mould and
mildew can also be present in the material or structure itself (e.g. wall cavity where they cannot be seen). Eliminating
the water source takes care of part of the problem. If you doubt the effectiveness of cleaning, replacement of all water-
damaged materials may be your solution.The decision to remove and replace affected materials should be made with
care by qualified individuals such as an independent construction professional. CGC does not require the removal of
SHEETROCK庐 Brand Gypsum Panels simply because they once were wet. However, if you have conditions for mould and
mildew growth and your gypsum board has gotten wet continuously for more than 24 hours or intermittently for many
days or weeks, the best assurance against mould and mildew growth is elimination of the conditions for growth along
with replacement of affected materials.
For additional detail to assist your decision, contact the FEMA office near you for more information on the repair of
water-damaged structures. Many university extension programs and public health departments can also provide
guidance on flood and moisture remediation measures.2,3,4
Summary We hope that this information and the additional references help you to select a strategy best suited to your project.
If you have additional questions, please contact us at 1-800-387-2690.
Additional Sources 鈥? Canada's Indoor Environmental Program (http://www.nrc.ca/irc/ie)
鈥? New York City Department of Health, http://www.ci.nyc.ny.us/html/doh/html/epi/epimold.html
鈥? United States Environmental Protection Agency, http://www.epa.gov/iaq/pubs/mold resources.html
鈥? Canada Mortgage and Housing Corporation, http://www.cmhc.ca/en/burema/gesein/abhose/abhose_ce08.cfm
鈥? Health Canada, http://www.hc-sc.gc.ca
Footnotes 4. Cambridge Emergency Notice SAFETY FIRST!
1. American Red Cross, After a Management Department, We shall not be liable for inci- Follow good safety and industrial
Flood: The First Steps, ARC City of Cambridge, dental and consequential dam- hygiene practices during
4476, FEMA L-198, Aug. 1992, Massachusetts, ages, directly or indirectly sus- handling and installing of all
http://www.fema.gov/library/lib http://www.ci.cambridge.ma. tained, nor for any loss caused products and systems. Take
08.htm. us/~EM/floodinf.html by application of these goods necessary precautions and
2. University of Minnesota not in accordance with current wear the appropriate personal
Department of Environmental Trademarks printed instructions or for other protective equipment as needed.
Health and Safety, The CGC logo is a registered than the intended use. Our Read material safety data
http://www.ci.cambridge.ma. trademark of CGC Inc. CGC Inc. liability is expressly limited to sheets and related literature
us/~EM/floodinf.html. is a licensed user of the replacement of defective goods. on products before specification
3. Iowa State University trademark SHEETROCK. Any claim shall be deemed and/or installation.
Extension, waived unless made in writing
http://www.exnet.iastate.edu/ to us within thirty (30) days
Information/Flood/ from date it was or reasonably
should have been discovered.
CGC Inc. EWB-0W95/05-02 CP
350 Burnhamthorpe Rd., W. (800) 565-6607
漏 2002, CGC Inc.
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