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Isover CWS 36 is a glass mineral wool slab supplied in 50–150 mm thicknesses. The strong, resilient and flexible batts are 455 mm wide to fit between standard wall tie spacing. Isover CWS 36 provides thermal performance in external masonry cavity walls to meet Approved Document L (England and Wales) and Section 6 (Scotland).


Resilient to moisture damage in storage, during transportation and on site during installation.


  • All Isover products are manufactured under Environmental Management System – ISO 14001.
  • Zero Ozone Depletion Potential (ODP), Global Warming Potential (GWP) <5.
  • The manufacturing process does not use or contain CFC's, HCFC's or other damaging gases.


All Isover products are manufactured under Quality Management Standard – ISO 9001. All Isover UK manufactured glass mineral wool insulation has achieved a 'good' rating within BES 6001 - the Responsible Sourcing of Construction Products Framework.

Recycled content:

Isover glass mineral wool insulation is manufactured from up to 80% recycled glass.


  • Made from rot-proof non-hygroscopic materials.
  • Will not sustain vermin, nor breed or promote fungi or bacteria.

Handling and storage:

Isover products are supplied fully palletised:

  • Weatherproof packaging for outside storage.
  • Reduced haulage costs.
  • Less handling therefore less damage.
  • Reduced storage space.
  • Packs remain clean and in good condition.
  • Faster loading, unloading and counting.

General information
Specification data
Product Reference

Isover CWS 36


50 mm

65 mm

75 mm

85 mm

100 mm

125 mm

150 mm

Face size

1200 x 455 mm

Standard product features

Thermal conductivity:

0.036 W/m·K.


Euroclass A1 fire rating when classified with BS EN 13501-1.

Third party certifications
  • BS EN ISO 9001 : Manufactured under BSI Quality Management. Certificate Number FM 674646
  • Certificate: 90/2465
  • Certificate: Manufactured under Environmental Management System ISO 14001. Certificate Number EMS 674645
  • Certificate: Manufactured under BES 6001 the Responsible Sourcing Framework. - Certificate Number 24756
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