Acoustic Plaster

Acoustic plaster is a spray-applied or trowel-applied surface treatment that provides sound absorption while maintaining a seamless, smooth-plaster appearance. Consisting of porous calcium silicate, mineral granules, or cellulose-based compounds, acoustic plasters achieve NRC values of 0.50–0.85 depending on thickness (typically 10–25 mm) and substrate. They are applied over mineral wool or a sound-absorptive substrate to maximize performance. Acoustic plasters are architecturally valuable because they allow curved surfaces, reveals, and complex geometries to be treated without visible joints or panels. Common in theatres, museums, lobbies, and high-end offices, acoustic plasters are tested per ISO 354 and are available from manufacturers such as BASWA, Sonacoustic, and Fellert. Installation requires specialist applicators and is more costly than panel-based systems, but the aesthetic benefits justify the premium in many design-driven projects.