Sources: RMC Research & Education Foundation, National Ready Mixed Concrete Association, Alexandria, Va.; CP staff
A new report, “Compilation of Acoustics Information for Concrete Construction and Other Materials,” assesses sound transmission class (STC), impact insulation class (IIC) and other ASTM standard-measured metrics driving wall and floor-ceiling assembly acoustic performance. The RMC Research & Education Foundation and National Ready Mixed Concrete Association enlisted the author, Cambridge, Mass.-based Acentech Inc., to organize and chart existing material and assembly data from disparate sources to ease building design professionals’ wall and floor-ceiling specification.
“This report, compiled by one of the country’s leading acoustical consulting firms, provides designers, owners, and contractors valuable information for producing buildings that deliver an enhanced standard of living by reducing noise within living and working spaces,” says NRMCA Senior Vice President, Structures and Codes Scott Campbell.
Acentech outlines acoustic performance of such wall or floor-ceiling assemblies as concrete pan joist or flat slab, concrete metal deck, insulating concrete form, concrete block, precast hollow core, wood joist and stud wall, and mass timber. It frames STC and IIC ratings in relation to International Building Code requirements. The former metric measures walls and floor-ceiling assemblies’ sound isolation performance in a laboratory and abides ASTM E901 and E4132 standards. IIC reflects floor-ceiling assembly measurements in a laboratory and is especially indicative of footfall noise in occupied spaces. In thicknesses or cross sections as low as 4.5 inches, cast-in-place or precast concrete and concrete masonry typically meet or exceed the IBC minimum requirements of STC 50 and IIC 50.
“Concrete has increasingly become preferred acoustically in the construction of floor-ceilings and walls in all building market segments due to high acoustics performance,” the report states. “Acoustics has become an integral factor in the construction of modern buildings. Nearly every market segment includes acoustical requirements, from multifamily residences to medical facilities to schools and universities, and most everything in between.”
“Acoustic considerations are an important factor in multifamily housing construction decisions and provide important privacy and quality of life benefits to future tenants,” adds RMC Foundation Chairman Rodney Grogan (Dunn Investment/MMC Materials). “This report provides data that, once again, demonstrates the value concrete brings to affordable and quality housing. The Foundation is pleased to continue its partnership with NRMCA and the Build With Strength team to provide this resource to the building community.”
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ASTM E33 COMMITTEE MEMBERS GAUGE ACCURACY OF ACOUSTIC TEST METHOD
ASTM International Committee E33 on Building and Environmental Acoustics is developing a new standard guide for estimating the accuracy of acoustic test methods through interlaboratory studies (ILS). The test methods are used to measure acoustical performance of wall systems, doors, windows and other building products or assemblies.
Committee member Robert Hallman notes that the proposed standard—WK81571 New Guide for Conducting an Interlaboratory Study to determine Precision Estimates for an Acoustics Test Method with Fewer than Six Participating Laboratories—is being developed to help E33 task groups with interpreting and presenting results from studies done by a smaller number of labs. This is necessary because there are so few labs and/or measurement teams that can perform many of the measurements that the E33 measurement standards require.
“Each test method is required to have a precision and bias statement but performing an ILS with fewer than six laboratories involves different statistical considerations than with larger groups,” says Hallman. “Also, for many E33 measurement standards, the several measured results are algorithmically combined into a single number rating, or classification. These classifications are the metrics our industry primarily cares about, but existing standards dealing with precision and bias do not address them within these classifications.” Although the standard will most strongly benefit E33 task groups overseeing the acoustic test methods, he adds, the end users of those methods will benefit from improved precision and bias statements as well.