Knauf Earthwool Dritherm 37 Cavity wall insulation slab 1200mm x 455mm

Knauf Earthwool Dritherm 37 Cavity Wall Insulation Slab is a glass mineral wool product manufactured using ECOSE® Technology, giving it a natural pale brown colour with low dust and a softer fibre texture. The slab is designed with a controlled fibre structure that provides a slightly oversized friction-fit between cavity wall ties, helping minimise air gaps and thermal bridging.

The insulation supports consistent thermal performance suitable for residential and commercial cavity wall systems and assists in meeting Building Regulations, including Part L requirements for energy efficiency. Its mineral wool composition offers vapour permeability and water-repellent behaviour, allowing moisture to drain through the cavity without transferring across the wall.

Dritherm 37 also provides natural acoustic absorption due to its open-fibre structure, helping reduce external noise. The slab is BBA Certified for suitability in masonry cavity constructions, offering proven long-term performance across a building’s service life.

Installation Guide:

• Ensure surfaces are clean, level, and free from debris
• Position the restraint strap according to structural design requirements
• Fix the strap using minimum 3.75 × 30 mm square twist nails or equivalent screws
• Secure to timber joists, rafters, or trusses at required spacing
• Bend or twist the strap if necessary to align with fixing points
• Check all fixings are tight and structurally secure before completion

Why Knauf Dritherm 37 Is a Smart Choice for Cavity Wall Insulation?

Knauf Dritherm 37 Cavity Wall Insulation is an excellent option for projects where reliable thermal performance, cost efficiency, and regulatory compliance are the main priorities. With its λ-value of 0.037 W/mK, A1 non-combustible rating, and ECOSE® Technology, it delivers dependable insulation performance suitable for most residential and light-commercial applications.

Dritherm 37 delivers high-quality cavity wall insulation at a more affordable price point, making it a popular choice for developers, homeowners, and contractors working on cost-sensitive builds. For many residential builds and extensions, Dritherm 37 easily meets U-value requirements without needing a premium insulation upgrade especially in 100mm to 150mm cavity walls.

Dritherm 37 is also an ideal choice for renovation projects where the existing building fabric uses insulation with similar thermal performance, ensuring consistency without unnecessary upgrades. Its slightly higher density delivers modest acoustic benefits by improving sound absorption for enhanced indoor comfort.

Is Dritherm 37 Suitable for Larger Cavities?

Yes, Wider cavities naturally improve thermal performance, so Dritherm 37 provides outstanding results in 125mm and 150mm cavities, offering excellent value without compromising compliance. If your existing building fabric uses insulation with similar thermal performance, Dritherm 37 is the perfect choice to maintain consistency and avoid unnecessary upgrades.