How to manage Sound Attenuation with Warmboard

Sound attenuation may required to attain code ratings or to mitigate sound issues for a client. The best practice in residential, multi-family and light commercial applications is to have the floor/ceiling assembly evaluated by one of several testing methods. Common methods of testing include field or lab testing, software modeling and estimating. Each method offers a different level of accuracy and cost. Usually these services are performed by an “Acoustical Consultant” to provide STC and IIC ratings. The higher the rating, the quieter the floor/ceiling assembly.

A Sound Transmission Class (STC) rates how well a building’s floor/ceiling assembly attenuates airborne sound, such as noise from stereos or human conversations. A common rating for standard residential assembly is 35-40 STC.

An Impact Insulation Class (IIC) is a rating of how well an assembly attenuates structure borne sound, such as noise generated from children running across the floor or dancing. A common rating for a residential floor/ceiling assembly is 35-45 IIC.

IBC Section 1207 mandates that all floor/ceiling assemblies in multi-residential buildings meet or exceed a rating of 50 for both STC and IIC.

While some design professionals specify light weight concrete to create a quieter living space, the APA (Engineered Wood Association) conducted a lab test with 1 5/8″ lightweight concrete and found little benefit overall to sound attenuation (APA document available upon request).

Assembly with concrete: STC 53, IIC 74

Assembly without concrete: STC 48, IIC 69

For Warmboard applications, there are a few solutions to increase STC and IIC ratings, depending on your needs:

• Sound Shark by Sound Seal

• QTSCU by QT Sound Control

• Privacy Ultimate Underlayment by Sound Isolation Company

• Homasote 440 Sound Board Barrier

• Iso Max by Kinetics

• Quiet Clips by Sound Isolation Company

• Genie Clips by Acoustigard

The products and methods we recommend are all practical solutions to help achieve a quieter living space. It is important to understand the sound industry as its products can be controversial. Your project may require a qualified consultant to help guide achieve your desired goals.