insulFib 3+

Thin and ultra-resistant 22 dB

The efficient, thin and ultra-resistant acoustic underlay - NEW

insulFib 3+ is a thin acoustic underlay which aims to reduce the impact sound transmission between the different floors of a building. It has to be placed under a floating sand and cement screed. Alternatively, it can also be placed under a liquid screed.

Recent tests carried out by the CSTB in accordance with NF EN ISO 717-2 certify the outstanding performances of insulFib 3+.


insulFib 3+ thin acoustic underlay under a floating screed

Two-component acoustic felt

insulFib 3+ is a bi-component acoustic felt coated with a highly resistant spunbond non-woven fabric with a thin adhesive overlap of ± 6 cm width. This product has an extremely low dynamic stiffness since its resonance frequency is only at < 50 Hz. This grants the product a remarkably good impact and high airborne sound insulation.

  • CSTB
  • QB
  • A+
insulFib 3+ thin acoustic underlay for floating screed
insulFib 3+ thin acoustic underlay for floating screed



3,5 mm


Blue (spunbond non-woven) + White (felt)


Spunbond non-woven fabric, Bi-component acoustic felt

Insulation against impact noise:

∆ L w = 22 dB CSTB 2019 AC19-26080209

Insulation against airborne noise:

∆ R w, heavy = 8 dB CSTB 2019 AC19-26080209


310 g/m² (under 4kg)

Dynamic stiffness:

s’t = 13 MN/m³

Thermal resistance:

R = 0,10 m²K/W (1 layer)


50 m x 1 m + blue adhesive overlap (6 cm)

Datasheet insulFib 3+ Read online Download