Isover Cavity Wall Slab (CWS) 32

Cavity Wall Slab (CWS) 32 is a glass mineral wool slab providing thermal performance in external masonry cavity walls. Manufactured with a water repellent binder, the strong, resilient and flexible slabs are 455mm wide to fit between standard wall tie spacing.

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Product Features

  • 1200 x 455mm mineral wool slab
  • Manufactured from up to 82% recycled glass
  • Manufactured with a water repellent binder
  • BBA Approved – certificate 18/5560

Fire Classification

Euroclass A1 Reaction to Fire classification according to EN 13501-1.

Product Specification

Thickness (mm) Length (mm) Width (mm) λD Declared thermal conductivity (W/m.K) RD Declared thermal resistance (m².K/W)
65 1200 455 0.032 2.00
75 1200 455 0.032 2.30
85 1200 455 0.032 2.65
100 1200 455 0.032 3.10
125 1200 455 0.032 3.90
150 1200 455 0.032 4.65

Product Benefits

  • Thermal Performance - Thermal conductivity of 0.032 W/m.K. Helps to reduce heat loss within the building envelope and decrease energy costs.
  • Sustainability - Manufactured from up to 82% recycled glass on a plant that uses 100% renewable electricity. For further details visit
  • BBA Certified - Cavity Wall Slab (CWS) 32 has been assessed by the BBA as fit for use in defined full fill and partial fill masonry cavity wall applications if installed, used and maintained as set out in the certificate. Please read the certification at for full details and restrictions.
  • Fire Classification - Achieves a Euroclass A1 Reaction to Fire classification, according to EN 13501-1.
  • Easy to Install - Slabs are 455mm wide to fit standard wall tie spacing for straightforward installation. No requirement for retaining discs when fully filling the cavity.

Key Considerations

When using Isover Cavity Wall Slab (CWS) 32, you need to satisfy yourself that use of the product meets all relevant national Building Regulations and guidance as well as local, national and other applicable standards relevant for your construction or application, including requirements in relation to fire and applicable height restrictions.
Please refer to the following product documents: