Roofing assemblies with DensDeck roof boards first to achieve industry-leading 61 STC and 49 OITC ratings

Georgia-Pacific Gypsum continues to innovate in the roofing industry with its DensDeck Roof Boards, which are the first gypsum roof boards tested to contribute to Sound Transmission Class (STC) ratings of up to 61 and Outdoor Indoor Transmission Class (OITC) ratings of up to 49 in roofing assemblies for commercial framed construction*. These high levels of sound attenuation are especially important as new code and building programs call for sound mitigation in wall and roof-ceiling assemblies, especially in high noise areas around airports, expressways, light rail and railroads and military bases.

“The new roofing assemblies we’ve configured and tested are an industry first. We achieved a 61 STC (49 OITC) performance with one specific assembly for commercial framed construction and used standard roofing installation techniques for all of the tested assemblies,” said Reinhard Schneider, technical manager, DensDeck, Georgia-Pacific Gypsum. “In addition to providing the durability and long-term performance customers have come to expect from DensDeck, we have verified significant sound remediation benefits.”

Introduced to the market 25 years ago, with hundreds of millions of square feet on the market, DensDeck Roof Boards from Georgia-Pacific Gypsum are the number one architecturally specified fiberglass mat gypsum roofing boards. Recent testing showed that in specific assemblies, DensDeck can help obtain superior STC and OITC ratings and can help meet UL Class A fire ratings, the highest rating for fire resistance under ASTM E-108.

STC and OITC ratings are measures of resistance of a building element (e.g., roof) to sound penetration based on different assumptions regarding the frequency content of the sound. Higher STC and OITC ratings indicate better sound resistance for the specific assumptions of the rating.

“Excessive noise indoors can interfere with sleep and voice communication, including television and telephone, or simply be a distraction and annoyance,” said Noral Stewart Ph.D., FASA, FASTM, INCE, of Stewart Acoustical Consultants and a spokesperson for Georgia-Pacific Gypsum. “Controlling sound is an essential part of any plan to provide a more comfortable environment for building occupants.”

Schneider added that the tested assemblies can be specified for new construction, as well as for remediation projects on existing buildings. For the optimum sound protection, the roofing configurations used in new construction include added layers of ToughRock gypsum boards or DensArmor Plus interior panels for interior ceilings.

Many standards, codes, and green building programs require or give extra credit by improving isolation from outdoor sounds, including:

  • ASHRAE 189.1
  • ANSI S 12.60 for schools
  • Facilities Guidelines Institute Guidelines for Design and Construction of Healthcare Facilities
  • Housing and Urban Development regulation 24CFR51B
  • Defense Department regulations for military housing
  • LEED for Schools
  • LEED for Healthcare.

In US Green Building Council LEED projects, DensDeck may qualify for credit contribution in Materials and Resources-Recycled Content (MR4) and Materials and Resources-Regional Materials (MR 5). Visit and click on the LEED Calculator link to determine credit contribution.

Editor’s Note:  Reinhard Schneider, technical manager for DensDeck Roof Boards, will be available in booth #30 at the 2011 International Roofing Symposium, September 7-9, Washington, D.C, for anyone interested in discussing this announcement.

*Testing of the new assemblies was completed at Riverbank Acoustical Laboratories in 2011.

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