Partial Fill Cavity Boards

Partial Fill Cavity Wall Insulation Boards

Partial fill cavity wall insulation is designed to fit within the cavity of masonry walls while maintaining a residual gap between the insulation and the outer leaf. This air space allows for moisture drainage, helping to protect internal structures from wind-driven rain and damp penetration—especially in exposed locations. Partial fill systems are a trusted solution in new build housing, extensions, and commercial walls where both insulation and moisture management are priorities.

At Insulation UK, we stock a range of high-performance rigid PIR and phenolic cavity boards from industry-leading brands like Kingspan and Recticel, all BBA certified and suitable for use in traditional brick-and-block construction.

Key Partial Fill Cavity Products:

Kingspan Thermawall TW50 is a rigid PIR insulation board with foil facings on both sides. It offers a thermal conductivity of 0.022 W/m·K, fits easily between wall ties, and maintains a 50mm residual cavity for moisture control—ideal for standard masonry wall construction.

Kingspan Kooltherm K108 is a high-performance phenolic cavity board faced with low-emissivity foil. With a thermal conductivity as low as 0.018 W/m·K, it's perfect for applications where space is limited but exceptional thermal performance is required. It’s designed for use in partial fill systems, particularly where a slim wall build-up is beneficial.

Recticel Eurowall Partial Fill is a PIR cavity insulation board with rebated edges for minimal thermal bridging and tight jointing. With a thermal conductivity of 0.022 W/m·K, it’s ideal for partial fill installations in new masonry cavity walls, offering a balance of moisture protection and efficient insulation performance.

Ideal For:

• Brick-and-block cavity walls in new builds and extensions

• Projects requiring a residual air cavity for moisture drainage

• Walls exposed to wind-driven rain zones

• Installations needing a balance of thermal efficiency and building durability

All partial fill cavity boards we supply at Insulation UK are available in multiple thicknesses and are BBA certified for compliance with UK Building Regulations. Whether you're looking for cost-effective PIR or ultra-slim phenolic performance, we offer fast nationwide delivery and expert support.