Chapter 2.3 - Influence of internal thermal insulation on the sound insulation of walls

Abstract

Adding any sort of lining to a building element, e.g., to a wall or floor, influences the sound transmission through that building element. In this chapter, the change of sound transmission or sound insulation caused by adding an internal thermal insulation lining to exterior wall is discussed. First, a short review of the physical phenomena related to the sound insulation of a wall with and without internal thermal insulation is given. This should help understand the wall’s ability to insulate indoor spaces from outdoor noise. Following, the measured sound insulation, described by the standardized weighted sound reduction index Rw, is presented for three types of linings on a masonry wall. Of the three types, the detached stud linings perform best and give the highest improvement when added to a wall (up to 20 dB), linings attached to the wall with furring strips show a lesser improvement (up to 4 dB), and the lowest acoustically performing linings are the panelized composite linings that even result in a worsening of sound insulation when they are attached over the entire surface. The role, the spectra of the outdoor noise sources, e.g., traffic noise, can play on the indoor levels is also touched upon. The sound insulation of the exterior wall with lining is put into perspective with the other elements of the exterior wall, such as windows and ventilators. The internal thermal linings do not only influence the sound transmission from outdoors to indoors but also the sound transmission from indoors to indoors. An example suggests how and why this should also be taken into consideration when selecting appropriate interior thermal insulation.