Performance
Measuring the performance of building systems exposed to moisture is difficult. Existing tests examine products under artificially created, static conditions. Building systems experience extremely dynamic conditions where steady-state conditions are rarely achieved.USG's Position on ASTM C473 and ASTM D3273
In the absence of specific tests for the broad category of construction products, the industry uses ASTM C473 and D3273 for this purpose. ASTM C473 measures water absorption of panels as a percentage of weight. ASTM D3273 measures resistance to mold growth on the surface of interior coatings when exposed to a hot and humid environment. These test results do not represent definitive installed performance in specific project conditions, but do provide indicative measures of performance.USG is actively working with academic and industry testing leaders to develop a new ASTM test methods specifically for building materials such as wallboard and acoustical ceiling tiles.Beyond Testing
The key to minimizing mold growth is controlling moisture. Moisture exposure can occur during all phases of the construction process and through the building life cycle from roof, wall and pipe leaks, gross water penetration of the façade, vapor diffusion and condensation, and capillary rise.Products Alone Cannot Control Moisture or Prevent Mold
All products become susceptible to mold growth under unfavorable conditions. However, proper management of moisture in the building and selecting products that are appropriate for the application conditions are the building owner’s most effective means of preventing moisture and mold damage.Systems Approach
Avoiding leaks and preventing excessive accumulation of moisture requires a systems approach to the design and construction of all building elements. USG provides comprehensive information regarding best practices to reduce the risk of moisture damage. USG is the leader in offering products and systems that address the full spectrum of performance needs for specific applications.USG Testing Services
Learn more about the testing services offered at our Corporate Innovation Center in Libertyville, IL.USG Product Solutions
USG offers a range of ceilings products, many of which are guaranteed mold and mildew resistant for their lifetimes, under normal conditions.
USG offers a wide range of solutions for tile and flooring, from cement and glass-mat gypsum and Fiberock® backers, to self-leveling floor underlayments, membranes and accessories that are versatile, easy to install and provide performance you can trust. Many of these products are also mold and mildew resistant, scoring a perfect 10 on the ASTM D 3273 test.
USG offers the industry's leading interior panels with active mold-inhibitors both on the paper and in the core. These gypsum panels are designed to inhibit mold growth by treating both the surface paper and the core with mold fighting agents. The following commercial panels score a 10 (on a scale of 0 to 10) for mold resistance under the ASTM guidelines at the time of manufacture.
USG offers structural concrete panels for floors that are lighter than precast and poured in place concrete. They are ideal for new construction, mezzanines and adding to existing buildings.
The following structural concrete panels are resistant to mold growth. Independent tests by a certified laboratory confirmed no mold growth, recording a rating of 0 (zero) as measured by ASTM G21 and a rating of 10 as measured by ASTM D3273.
Myth vs. Fact
FACT: There are simply too many food sources in a residential project to prevent mold from growing by eliminating just one. Mold will grow on wood studs, insulation, and drywall, just to name a few materials. The most effective way to control mold is to control moisture.
FACT: Some level of moisture is indeed present at most construction sites, but proper storage and handling of during the building process, combined with best practices implemented during the design, construction and operational phases help prevent mold.
FACT: For years, the U.S. EPA has consistently stated to control mold, you must control moisture. USG is part of the Responsible Solutions to Mold Coalition, a group of building associations fully support the fact that moisture is the leading, and controllable, factor contributing to mold growth.
FACT: Mold-resistant products are effective only when used in conjunction with sound design and construction practices. When moisture is limited during the construction phase, mold-resistant products act as extra protection against mold growth when moisture (condensation, steam, dampness) is present.
FACT: Mold has been around basically forever. The more recent increase in attention to the issue has mainly been due to the hurricanes which have affected the Gulf Coast in recent years. From a construction standpoint, increased attention can be attributed to the increasingly demanding construction schedules leading to building materials being exposed to the elements before the project is properly closed in.
Resources and References
Design & Specifications
Storage & Handling
Application & Finishing
Final Storage & Handling
This comprehensive book set provides the building industry with the latest and best practical information on how to apply building science principles to structures as systems in cold, hot-humid, hot-dry/mixed-dry, and mixed-humid climates.
- Building Knowledge Inc.
- Building Science Corporation
- IBACOS Integrated Building and Construction Solutions
- American Society of Heating, Refrigerating, and Air-Conditioning Engineers
- Gypsum Association
- IAQA - Indoor Air Quality Association
- John F. Straube, “Moisture in Buildings,” ASHRAE Journal, January 2002.
- Joseph Lstiburek, “Moisture Control for Buildings,” ASHRAE Journal, February 2002.
- Lewis Harriman, “Preventing Mold by Keeping New Construction Dry,” ASHRAE Journal, September 2002.
- Sarah Armstrong, “The Fundamentals of Fungi,” ASHRAE Journal, November 2002.
- Chapter 17, Moisture Control in Buildings – Construction Principles and Recommendations, New Residential Buildings, ASTM Manual, MNL18, 1994
- Moisture Analysis and Condensation Control in Building Envelopes, ASTM Manual MNL40, 2001
- Moisture Problems in Manufactured Homes – Understanding Their Causes and Finding Solutions, Manufactured Housing Research Alliance (MHRA), 2000
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