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ROCKWOOL® Full Fill Cavity Batts

ROCKWOOL® Full Fill Cavity Batts

ROCKWOOL Ltd Third party certifications:
  • QA Certificate

    QA Certificate

    Certificate type

  • BBA Agrément Certificate

    BBA Agrément Certificate

    Certificate type

Full-fill stone wool insulation for masonry cavity walls.

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Full fill insulation for masonry cavity walls.


ROCKWOOL® Full Fill Cavity Batts are a stone wool insulation solution for masonry cavity walls, suitable for use in new builds and extensions. Lightweight and easy to handle, the batts are simple to install and provide a close fit against brick and blockwork. ROCKWOOL Full Fill Cavity Batts are non-combustible and contain water repellent additives which prevent moisture transmission between the outer and inner leaf.

 The NHBC accepts the use of ROCKWOOL Cavity Batts, other than in very severe exposure locations with fairfaced masonry, provided it is installed, used and maintained in accordance with the BBA Certificate, in relation to NHBC Standards, Chapter 6.1, External masonry walls. Building standards have also recognised that where party cavity-walls between connected buildings are untreated, considerable heat can escape through them. Using ROCKWOOL Cavity Batt to fully fill the party wall will reduce the u-value to 0.00 W/m2K.

Features and benefits:

  • Euroclass A1 non-combustible.
  • Water repellent - prevents water transmission from outer to inner leaf.
  • Acts as a cavity barrier - no additional TCBs required.
  • Close fit against blockwork.
  • Dimensionally stable and robust - preventing slumping and sagging.
  • CE marked to BS EN 13162:2012+A1:2015 • BBA certified (BBA certificate number 94/3079).

Water resistance and moisture:

The product will resist the transfer of water across the cavity. The orientation of the water repellent fibres prevent water crossing the wall construction, provided the batts are correctly installed and sound building techniques are applied to the cavity wall construction (see installation notes). Any water penetrating the outer leaf will drain down the surface of the batts.


Will contribute to limiting the risk of condensation.


ROCKWOOL stone wool is highly resilient, durable and dimensionally stable, maintaining its thickness and shape over time. Moreover due to its fibre structure and overall flexibility, stone wool can easily fit into available spaces, helping in avoiding unplanned air gaps, cracks or other installation errors in the final construction, ensuring stable performance over time.


  • Approved Document L (2013 edition England and 2014 Wales) – U-value requirements for walls:
  • New build dwellings: England 0.25-0.18 W/m²K / Wales 0.21-0.18 W/m²K.
  • New build non-domestic: England 0.26-0.22 W/m²K / Wales 0.26-0.22 W/m²K.
  • Extensions to dwelling: England 0.28 W/m²K / Wales 0.21 W/m²K.
  • Extensions to non-domestic: England 0.28 W/m²K / Wales 0.26 W/m²K.

General information


Mineral wool




Length x width x thickness.

1200 x 455 x 50 mm

1200 x 455 x 75 mm

1200 x 455 x 80 mm

1200 x 455 x 100 mm

1200 x 455 x 150 mm

Uniclass 2015

Pr_25_57_06_50 Mineral fibre slab insulationPrimary


F30/10 Full fill cavity insulation

F30/150 Full fill cavity insulation

Specification data - Mineral fibre slab insulation Enhanced data

General requirements

Insulation products generally.


To BS EN 13162; BS 6676-1; ISO 14001.

 Manufactured to BS EN 13162 and conforming with BS 6676-1.

Thermal conductivity (maximum)

0.037 W/m·K.

Thickness (minimum)

Thickness range*: 50mm – 250mm (Non-standard thicknesses subject to MoQ).

50 mm.

75 mm.

80 mm.

100 mm.

150 mm.



Fire performance

To BS EN 13501-1, Euroclass A1.



0.00 W/m²K.

Using ROCKWOOL Cavity Batt to fully fill the party wall will reduce the U-value to 0.00 W/m²K.

Third party certifications

  • Certificate: 94/3079
  • LPCB approved : To BS EN 13501-1 – Class A1 Non-combustible (cert. 022e)
  • CE : Key and Kite marked to BS EN 13162
  • Approved