Acoustic plaster is a material made of fibrous and porous materials that absorb sound and help reduce sound reverberation within spaces.
Materials and physical characteristics
Acoustic plaster systems usually come in pre-made panels that require final finishing on site.
They usually include the following:
a thick sound absorptive backing layer made of mineral wool, glass fibre, natural fibre or foam.
a porous (acoustically transparent) and more rigid base layer.
a thin finish layer of plaster trowel or spray applied to the backing layer.
a second thin layer can be applied to provide a finer finish.
The thickness of the panels ranges from approximately 10mm to 70 mm. They can either be fixed to a hard surface or as part of a suspended ceiling (in which case, the thickness of the whole system can reach approximately 220 mm).
Advantages and use of acoustic plaster
Acoustic plaster systems are usually installed on the ceilings, the soffits and sometimes the walls.
Their advantages are:
they have a seamlessand smooth appearance.
they can be curved or shaped to follow a custom design.
they can sometimes integrate heating and cooling systems.
although white is preferred most of the time, they can be tinted or painted (with approved paint) in different colors.
Acoustic plasters are generally fire-resistant and can be made moisture resistant.
Lighting systems, sprinklers and audio systems can also be integrated.
Sound absorption performance
The sound absorption performance of acoustic plasters depends on:
the material of the backing layer.
the thickness of the backing layer.
the porosity of the surface finishes.
if fixed to a suspended ceiling, the depth of the ceiling cavity.
The sound absorption characteristics of acoustic plasters are considered for each square meter of material and can achieve a large variety of performances ranging from Class D to Class A.
As mentioned above, plasters can also be painted provided the paint is approved by the manufacturer. This is because paint can modify the porosity of the finish layer and change the sound absorption capacity of the system.
Some plaster systems use natural or recycled materials (such as recycled glass granulate) for the backing layer.
The plaster finish can be made from glass or marble granular aggregate, which is a secondary material obtained from the production of natural stone.
Installation and workmanship
Installing acoustic plaster systems requires a high level of workmanship to obtain the sound absorption performance desired and avoid cracks appearing with time.
Suppliers either have in-house and trained installers or certified installers.
See below for examples of suitable acoustic plasters.