Metal Building insulation greatly reduces the level of both exterior and interior noise by preventing transmission of exterior sounds to the interior of the building and absorbing reverberating sounds within the building. This fact sheet discusses the fundamentals of acoustical performance and shows how to improve sound control in typical wall and roof assemblies through the use of fiber glass insulation.

Metal building insulation has been used for many years to thermally insulate the walls and roofs of metal buildings. An additional benefit is that it provides a better acoustical environment both inside and outside the building. Metal building insulation can absorb interior noise to provide a quieter work environment. It can also decrease the amount of noise transmitted into or out of a building. Because of the porous nature of metal building insulation, it is an excellent absorber of sound. It can reduce noise levels in a building up to 5-6 dB. This same sound absorbing property is used to reduce the amount of sound that is transmitted through a wall or roof. Thus, it can reduce equipment noise transmitted to neighbors. It can also reduce outside noise so that building occupants are not disturbed by exterior noise sources such as traffic.

Sound Absorption Coefficient

The sound absorption properties of a material are expressed in terms of a sound absorption coefficient. This coefficient typically ranges from 0.05 to 1.20. The higher the coefficient the better the material absorbs sound. Sound absorption coefficients are measured at several frequencies since it varies with frequency. A material with an absorption coefficient of 0.66 at a particular frequency, means that 66% of the sound that strikes that material is absorbed or conversely 34% of the sound is reflected back into the room. Metal building insulation is an excellent sound absorber with coefficients ranging from 0.20 to 1.20.

Noise Reduction Coefficient (NRC)

A single number rating has been established to express the ability of a material to absorb sound at multiple frequencies. This single number rating is called the noise reduction coefficient (NRC). Again, the higher the NRC value, the better a material absorbs sound. NRC values for faced metal building insulation range from about 0.75 to 0.90.

Sound Transmission Loss

The ability of a wall or roof to reduce the amount of sound transmitted through it is called sound transmission loss. Sound transmission loss is expressed in decibels (dB) and it also varies with frequency. Most materials and constructions reduce the transmission of high frequency sounds more than low frequency sounds. When building a wall or roof it is imperative that there are no air (sound) leaks in the construction. Sound leaks can drastically reduce the effectiveness of a wall to reduce the transmission of sound from one space to another. The construction should be as tight as possible. Where gaps exist, they should be filled with a flexible sealant such as a non-curing Butyl, siliconized acrylic latex or an acrylic latex.

Sound Transmission Class >>