Retrofit structural insulated panels increase sound transmission loss of existing single family houses impacted by highway noise.

Abstract

Owners of newly constructed houses complained of interior noise from a nearby interstate highway. The houses were constructed using structural insulated panels (SIPs) as opposed to conventional 2x4 wood studs. The SIPs are composed of 3.5 in. of expanded polystyrene insulation sandwiched between two layers of oriented strand board (OSB) and exhibit higher thermal efficiency than conventional construction. Sound transmission loss testing of the standard SIPs, however, reveals relatively low acoustical performance especially in the 630 Hz range. This characteristic acted as a band pass filter allowing only a portion of the broadband traffic noise to enter the house. The observed traffic noise inside the house had a clear tonal quality adding to the annoyance of the traffic noise impact. After consideration of several remedial options the builder decided to retrofit the exterior of the impacted houses using a combination of standard resilient channel, insulation, and additional OSB. Some window replacements were also required. These treatments resulted in reduced interior noise levels especially in the 630 Hz range.