insulit Bi+8

Foam + felt, comfort and security 28 dB

The underlay for a superior acoustic comfort between floors

insulit Bi+8 is a thin underlay dedicated to the acoustic floor insulation between the dwellings: it limits the transmission of impact and airborne noise between floors. insulit Bi+8 replaces the successful insulit Bi+7, from this previous version we preserved the easy installation while we improved the product resistance and its acoustic performance.

This upgraded acoustic underlay belongs to our premium range. Recent tests carried out by the BBRI according to EN ISO 717-2 are proving its outstanding performance. When installed on a concrete slab, under a floating screed of ± 6 cm thickness, the acoustic noise insulation mesured is ∆Lw of 28 dB! To achieve even better results, we recommend using a thermal levelling screed.

insulit Bi+8 acoustic floor underlay under floating screed

Foam + felt: unique acoustic performances!

insulit Bi+ 8 is made of an embossed, physically crosslinked polyolefine foam (thickness ≥ 3,5 mm) with closed micro cells, combined to an acoustic felt with a low dynamic stiffness (thickness ≥ 5 mm). A bi-component underlay is far more efficient than a single layer acoustic solution: the foam and the felt altogether are able to cover a much larger frequency range, where the felt absorbs low frequencies and the foam absorbs medium and high frequencies.


  • Reduction of impact & airborne noises
  • In rolls, quick and easy installation
  • Highly efficient
  • Tape provided to maintain the overlaps
  • Physically crosslinked polyolefin: guaranteed longevity
  • Closed microcells
  • Thin, light and flexible
  • Low dynamic stiffness = better acoustic performance
  • Low creep
  • Recent BBRI reports = guaranteed good results
insulit Bi+8 acoustic floor insulation under floating screed
  • BBRI
  • VOC
insulit Bi+8 roll of acoustic underlay
insulit Bi+8 roll of acoustic underlay



Physically crosslinked polyolefin
and acoustic polyester felt


≥ 8,5 mm under 1,5 kPa


Orange (foam) / Anthracite (felt)

Impact noises insulation:

ΔLw = 28 dB on a bare slab with no pre-screed
(ISO 717-2:2013 ; EN ISO 10140-3:2010)

Dynamic stiffness:

st = 8 MN/m³ (EN 29052-1)

Tear resistance:

50 – 50 N (EN 12310-1)


≤10 % under 2 kPa (tolerance 10%)

Thermal resistance:

R = 0,26 m²·K/W (EN 12667:2002)

Thermal conductivity:

λ = 0,0356 W/m·K at 10°C (foam) (EN 12667:2002)
λ = 0,0353 W/m·K at 10°C (felt) (EN 12667:2002)


30 m x 1,50 m = 45 m²


±320 g/m² (15 kg per roll)


±15 kg


Junction is made with an included kraft tape

Datasheet insulit Bi+8 Read online Download