Hardwood Floors February/March 2025

By Jared Kress

Acoustic ratings often are misunderstood, leading to confusion for both consumers and professionals in the flooring industry. Whether it’s about selecting the right underlayment, deciphering laboratory ratings versus real-world performance, or grappling with unrealistic building requirements, the gap between expectation and reality remains challenging.

THE ROLE OF UNDERLAYMENT IN ACOUSTIC PERFORMANCE

Underlayment is crucial in enhancing acoustic performance, but it’s not a standalone solution. Instead, acoustic results stem from the combined performance of the entire floor/ceiling assembly. This floor/ceiling assembly includes the type of flooring, underlayment, and the construction of the building itself. Consider two scenarios: • An engineered wood floor with an acoustic underlayment installed in a wood-frame, low-rise condo building. • The same setup is used in a high-rise concrete building with a suspended concrete slab, drop ceiling, insulation, and layered drywall. Despite identical flooring and underlayment, the acoustic performance in both will be significantly different. Why? The additional structural layers and greater separation between units in the concrete building will reduce sound transmission far more effectively than the underlayment alone used in the wood frame building. This illustrates the importance of viewing underlayment as one piece of a much larger puzzle. While underlayment plays an important role, the building’s construction has an outsized impact on acoustic performance. Acoustic ratings, often derived from laboratory tests, do not always reflect real-world performance. Labs test flooring systems under controlled conditions, including ideal concrete slabs, drop ceilings, and insulation. These conditions rarely are replicated in actual building environments. For instance, a lab might assign an Impact Insulation Class (IIC) rating of 72 to a specific underlayment. However, this rating assumes the lab’s perfect setup. When the same underlayment is installed in a wood-frame construction, the actual IIC of the entire floor/ceiling assembly may fall short due to structural differences. This discrepancy underscores the need for consumers and building management to understand that lab ratings on specified products are not applicable for all construction methods. LAB-TESTED ACOUSTIC RATINGS VS. REAL-WORLD PERFORMANCE

PHOTOS COURTESY OF METROPOLITAN FLOORS

the magazine of the national wood flooring association

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