Excessive sound and noise have become such an inundating part of our daily lives that we may hardly notice it (except of course when trying to put the kids to sleep or giving a presentation on Zoom). And nowadays noise comes at us from so many places that at times it’s hard to even identify an exact source. To reduce this noise assault on us when indoors, building codes impose sound transmission limits and new construction must demonstrate compliance.
Ensuring noise mitigation is an important consideration for designers and engineers throughout the design process from both aesthetic and obligatory standpoints (and something occupants certainly appreciate in the long run). For wood assemblies there is at least one tool, and now an app, that can provide some sound (literally) information for those involved in the design and construction process.
To simplify determining acoustic compliance for wood floor-ceiling assemblies, the American Wood Council recently released a new mobile app to calculate sound transmission based on “Technical Report (TR) 15, Calculation of Sound Transmission Parameters for Wood-Framed Assemblies.”
Building codes stipulate minimum requirements for noise transmission through common interior walls and floor-ceiling assemblies that separate dwelling units from either public areas or adjacent dwellings. The International Building Code, commonly used throughout the U.S., provides two parameters to establish minimum acoustical requirements: Sound Transmission Class (STC) and Impact Insulation Class (IIC). Although it “sounds” a little technical, STC is a measure of the attenuation of sound waves that initiate as air-borne sound and pass through wall or floor-ceiling assemblies. Meanwhile, IIC is a measure of the assembly’s ability to insulate against structure-borne sound waves generated when an object strikes the opposite surface of the assembly or otherwise induces sound waves directly into the assembly.
Compliance with these two requirements may be demonstrated either through testing, which can be expensive, or through engineering analysis based on empirical test data from other similar assemblies. AWC’s TR 15 report provides a background on sound transmission and building code requirements, creation of the empirical engineering model, and then simplifies how wood-framed floor-ceiling assemblies can comply with the acoustical requirements. The free Acoustics App takes it a step further, making it even easier for building officials and designers to determine which wood-frame floor-ceiling assemblies comply with code-specified acoustical requirements.
The app utilizes the AWC empirical model, based on actual acoustic performance test data of wood-frame floor-ceiling assemblies, to estimate STC and IIC values. With the results from the app in hand, compliance with code-required sound transmission parameters can be easily demonstrated. It is available in the Android, iOS and Windows app stores.
Development and implementation of the Acoustics App is the next step in AWC making simplified tools available to the design and wood-using community to identify and comply with these important sound requirements. For those interested, AWC also offers an eCourse that covers the basis for the calculation-based analysis approach. The class is accredited by the International Code Council (ICC) and approved by the American Institute of Architects (AIA) for continuing education credits.
While we can’t use the Acoustics App itself to reduce the noise that reaches our ears, we can at least have assurance that wood-frame assemblies specified for the buildings in which we live, work, and visit are protecting us by meeting sound transmission requirements.