Isover Cavity Wall Slab 36 – 100mm

Isover Cavity Wall Slab 36 – 100mm is a high-performance glass mineral wool insulation slab, purpose-engineered for external masonry cavity walls in both residential and commercial construction. Supplied by Minster (STARK Building Materials UK Limited), this BBA-certified product meets and exceeds UK thermal building regulations (Part L), making it a trusted choice for builders, contractors, and DIY renovators tackling new builds and retrofit cavity wall insulation projects.

Key Features and Specifications

• Material: Glass mineral wool (non-combustible)
• Thickness: 100mm
• Dimensions: 1200mm (L) × 455mm (W) × 100mm (T)
• Pack contents: 12 slabs — 6.55m² coverage per pack
• Thermal conductivity (λD): 0.036 W/m.K
• Thermal resistance (RD): 2.75 m²·K/W
• Fire classification: Euroclass A1 — non-combustible (highest attainable rating)
• Certifications: BBA Approved (certificate 18/5560), CE Marked to EN 13162, UKCA Marked
• Indoor air quality: Eurofins Indoor Air Comfort® Gold Certification
• Recycled content: Up to 75–82% recycled glass
• Manufactured using 100% renewable electricity
• Width: 455mm — pre-sized to fit standard wall tie spacing; no retaining discs required for full-fill installations
• Water-repellent binder: Resists moisture ingress and retains insulating properties over time
• Standards: Manufactured under ISO 9001 and ISO 14001

Applications

• Full-fill and partial-fill external masonry cavity wall insulation
• New build residential and commercial construction
• Retrofit cavity wall insulation upgrades to improve U-values
• Projects requiring compliance with Part L Building Regulations (England & Wales)
• Situations where a non-combustible, fire-safe insulation is specified
• Acoustic improvement in party walls and external walls

Why Choose This Product

The Isover CWS 36 100mm delivers a proven combination of thermal efficiency, fire safety, and ease of installation. The semi-rigid, flexible slabs cut cleanly with a knife or saw, slot snugly between standard wall ties without additional fixings, and resist moisture — so performance is maintained for the life of the building. With up to 82% recycled glass content and plant-wide renewable electricity use, it is one of the more sustainable cavity wall insulation options available. BBA approval and Euroclass A1 fire rating give specifiers and building control officers the confidence they need.

Delivery in and Around London

Minster delivers the Isover Cavity Wall Slab 36 – 100mm across London and the surrounding region. Inner London boroughs served include Croydon, Lewisham, Southwark, Camden, and Hackney. Greater London areas — including Enfield, Bexley, Redbridge, and Barnet — are also covered. Deliveries extend into the surrounding counties of Kent, Essex, Surrey, and Hertfordshire. Trade quantities are welcome, and bulk orders can be arranged to suit project schedules. Contact our team for availability and lead times.