Sound transmission is a common acoustic issue that can impact educational, commercial, and residential structures. Traffic, trains, aircraft – and neighbors – are typical sources of exterior sound. Sounds produced by talking, HVAC systems, and appliances are the major causes of interior sound. Low-frequency noises penetrate walls, roof, doors, and windows much more efficiently than do high-frequency noises. On the other hand, people hear high frequency sounds better and these sounds are carried through cracks and vents better. When any sound reaches a level where it is undesirable, it becomes noise.

Selecting appropriate building materials, understanding system design, and using effective construction technologies are the key to creating successful acoustic design. When designing a space to create a favorable interior acoustic quality, wall partitions, ceiling systems, and floor assemblies designed for the specific use of that space achieve the most effective sound control. Although the best method to reduce exterior noise is not to build near the noise source, in many instances, that is not possible, so the shell of a structure must be designed to keep noise out. It is generally more efficient and cost effective to take noise into account in the design phase rather than after starting construction as remodeling is much more costly and time consuming.

The STC (Sound Transmission Class) rating system, introduced in 1961, rates the ability of walls, doors, windows, and other partitions for their effectiveness in resisting airborne sound transfer. STC is the decibel reduction (dB) in noise a material/assembly can provide. In general, the higher the STC rating, the more effective the wall assembly is at reducing sound transmission of the most common frequencies. STC ratings, however, can be misleading because they are based on a logarithmic scale. The difference of around 20 in STC ratings of ICF walls vs. framed walls does not mean the ICF is 60% better, but roughly FOUR times better.

While an ICF wall typically has a 55 STC rating, other structural elements such as windows, doors, and exterior wall penetrations affect acoustic efficiency and should have good weather stripping and caulking installed around them for effective sound insulation. Consider thicker glass and wider airspaces between panes of glass in windows to lower sound transmission. Important factor when choosing doors include amount of insulation, core material, door weight, presence of window panes, and quality of seals and weather stripping.

Building any project with Insulating Concrete Forms will minimize sound transmission from exterior sources. ICF walls also provide a safe and secure structure, are comparable in cost to wood construction, and can cut energy costs significantly. Consider ICF walls for your next project!