NBS Source
557 Acoustic Cavity Closer


Designed for use as an acoustic closer for party walls. It helps reduce flanking noise transmission at the junction of internal separating and external cavity walls and is protected by its integral DPC.

Manufactured from tissue faced rockfibre slab laminated to black polyethylene DPC. The DPC forms a 40 mm flange on each side of the insulation and a 100 mm flange at the bottom edge.

To suit external cavity of 50–150 mm.

Meets the requirements of Building Regulations (E&W) Approved Document E (2003 edition) and NHBC standards.


  • Offers 60 minutes fire resistance to BS EN 476-20.
  • Strong yet flexible design.
  • Single width suits most applications.

General information

Uniclass 2015

Pr_25_80_80_79 Sleeved mineral wool cavity barriersPrimary


F30/18 Cavity closers

F30/180 Cavity closers

Product range

Acoustic Insulation

Specification data - Sleeved mineral wool cavity barriers

Product Reference

557 Acoustic Cavity Closer

Standard product features

Insulation length x width:

1200 x 260 mm.

Thermal conductivity:

0.035 W/mK.


1.42 W/m²K (50 mm).

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