The 85mm Dritherm 37 Cavity Batts (4.37sqm, 455 x 1200mm) are high-performance glass mineral wool slabs engineered specifically for full-fill masonry cavity wall insulation in new build and extension projects. Supplied in a pack covering 4.37 square meters, each batt measures 455mm in width by 1200mm in length with an 85mm thickness, designed to friction-fit snugly between standard vertical wall ties without slumping.
 
Manufactured with an exceptional thermal conductivity (lambda) value of 0.037 W/mK, these semi-rigid batts deliver dependable thermal efficiency to help external cavity walls easily comply with modern building regulations. The glass mineral wool matrix is treated with a water-repellent additive to prevent moisture transmission across the cavity, ensuring that water passing through the outer leaf cannot bridge to the inner blockwork.
 
In addition to their thermal properties, the batts achieve a Euroclass A1 non-combustible fire classification—the highest safety rating available—meaning they will not contribute to the development or spread of a fire. They also offer excellent acoustic performance to help reduce airborne noise traveling through the building envelope. Whether you are working on a residential housing development or a commercial build, these trade-quality cavity batts ensure long-lasting structural, thermal, and fire-safe integrity.