Noise problems associated with flooring range in transmission from voices, television and music to footfall impact and plumbing. The proper installation of a sound reduction system during the construction process can be a proactive solution to help prevent issues that could otherwise be very difficult and expensive to resolve.

Determining the IIC Rating

Before working with sound control products, installers should carefully consider the building code requirements for the project’s jurisdiction to ensure that the appropriate sound reduction performance properties are achieved.

When determining which type of sound reduction product is most appropriate for the desired installation, one should begin by examining the targeted Impact Insulation Class (IIC) rating required for the specific project. This rating is measured in an acoustic lab through a tapping machine with steel-faced hammers, which evaluates the sound-insulation properties of a building’s elements to determine the effectiveness of floor coverings in reducing impact sound transmission through concrete floors.

To conduct the test, two vertically adjacent exam rooms—the source and the receiver—are installed and separated by a standard concrete floor. Designed so the only significant sound radiation entering the receiving room is from the standard concrete floor, the tapping machine strikes the test floor material and generates sounds between 125 to 4,000 Hz. The acoustic lab engineer plots the results of each tap on a graph, compares the results to the reference assembly and then determines the IIC rating from comparing these two tests. The IIC rating with the higher number shows the better performance.

Adhesives Versus Underlayments

The pros and cons of choosing an adhesive versus an underlayment mat for sound reduction go hand in hand. For some, adhesives are the preferred method for sound control because they take the place of costly, time-consuming underlayment mat systems by allowing for faster, more effective tile or stone installations. However, adhesives are not ideal for all types of floor coverings.

Underlayment mats for sound control often include a wide array of mat thicknesses and IIC values, making them possible to be used in all types of flooring projects rather than limited to tile or stone. Both adhesives and underlayment mats typically work to also eliminate the transmission of substrate cracks from transferring to the finished floor.

How to Choose One Product Over the Other

After determining the appropriate sound reduction performance properties that will be achieved with the installation, installers should then examine the physical characteristics of the sound control product that is being considered for the application.

When there are several competing products with similar sound ratings, a contractor should compare each product’s Delta IIC results to determine the sound performance the tested product will actually provide to the substrate.

Typically tested on a 6-in.-thick (152 mm) slab, the Delta IIC test begins by testing a full installation assembly with nothing above or below the concrete. After this initial test, a soundproofing product is installed directly to the concrete and the normalized impact sound pressure levels are measured again. The Delta IIC rating is the performance gain between the first and second test, with the higher number showing better performance.

As a rule of thumb, underlayment sheet mats tend to work best under other types of glue-down finishes, such as hardwood, making them more versatile when various finishes require sound control. Adhesive products are best suited for ceramic and porcelain tile finishes as well as natural stone. They are also ideal for renovation projects where finish heights have already been established due to their thinner system profile build up.

Things to Consider

Soundproofing is an important element of commercial and residential buildings, such as apartments, condominiums, hospitals or offices, which require minimal impact noise from floor spaces above while providing comfortable levels for occupants. Additionally, from a building owner perspective, a recent study by David M. Sykes, Ph.D., on how acoustics affect workers’ performance in offices found that soundproofing can increase worker concentration by 48% and employee stress can be reduced by 27%.

Although it is up to the architect to specify soundproofing in their design plans, it’s recommended that installers working onsite recommend products that could save their peers thousands of dollars in the long run. This is because many soundproofing solutions are meant to be implemented during construction and may require permanent modification to install after the fact.