STY 325 Acoustic

Sty 325 is a natural plaster, applied to prevent noise/sound problems to neighbouring walls, elevators, generator rooms, offices, schools, hotels..ect. STY 325 is for professional use. Suitable for interior wall surfaces, bricks, aerated concrete, pumice walls and ceiling.


  • Acoustic insulation
  • Excellent adhesion
  • Breathable
  • Environmentally friendly products
  • Flexible, splinter proof
  • Light weight on the structure
  • Class A fire resistance
  • Easy to prepare and apply
  • Long lasting
  • The exact solution to the problems
  • Economic

Technical Specifications

Dry unit density(on wall)≤450 kg/m³
Compressive strengthCSI/CSII
Capillary water absorption Wc1
Fire ClassificationA2
Airborn Sound ReductionRw 50/56 dB



Before the application it is recommended to cover window sills, doorsteps, window and door fixtures and any element that will not be covered by the plaster. STY 325 can be applied by machine spraying the material onto the wall or by hand. If applied on the ceiling, STY 325 must be applied with plastering machine, we do not recommend hand application. It is fundamental to wet the surface, in particular during summer season and in case of walls exposed to sun. If the surface was treated with a primer, it is not necessary to wet the substrate. During summer season, apply the product in the cooler hours of the day, away from sun. Do not apply with imminent threat of rain or ice, in conditions of strong fog or with relative humidity higher than 70%. If applied internally, it is necessary that the external surface does not absorb water. Otherwise, treat the surface with a breathable water repellent product. In presence of exposed walls do the same application. STY 325 should be applied in an equal amount to the entire surface. The first layer must be applied by spraying as a thin layer. After it dries the material can be applied in layers. Use wooden or aluminium plastering lath as thickness guide to obtain the required thickness. These have to be removed immediately after the application of the last layer. To protect against cracking, galvanized mesh wire or 10x10 mm plaster net(mesh) should be used at junctions between concrete and wall construction elements. Galvanized wire mesh or 10x10 mm plaster net(mesh) should be used after 3 cm thickness. The net must be dipped into the plaster at about half of the total thickness and, if necessary, it must be used irrespective of the thickness even in case of application on panels, wood, plasterboards or to unstable substrates.To secure corner and angles, in multi floor application, use steel corner beads. After application the surface should be levelled, in case of gaps it can be adjusted by a trowel or sponge. When smoothing the plaster, do not push STY 325 that much against the wall. This is required to preserve the porosity of the plaster. To smooth, use a strike off bar, in horizontal and vertical way, to obtain a regular surface. Be sure that STY 325 is completely dried before final coatings applications (paints, every kinds of other coating materials). Only water based primer and paints should be used if the surface will be painted. If the surface will not be painted or will be painted later, until that time a water based transparent primer should be applied to the surface to protect the surface from external weather conditions. All works carried out outside must be performed in rainless weather, when insolation is not too high and wind is weak. If it is necessary to carry out works in unfavourable conditions, use appropriate shields, reducing the impact of weather factors. Plastered rooms must be ventilated, however it is necessary to prevent draughts and prevent the mortar from drying up to quickly as a result of sunlight or heating.


Classic Insulation System

Styronit Natural Insulation System