120mm STEICO Special Dry Wood-Fibre Insulation Board - Sarking & Sheathing Board - 1880mm x 600mm

120mm STEICO Special Dry is a multi-purpose, rigid wood-fibre insulation board manufactured using the modern Dry Process. It is designed to be installed on top of rafters (sarking) or on the outside of timber frame studs (sheathing). Because it is produced in a dry process, it can be manufactured in significantly greater thicknesses than the wet-process equivalent. The STEICO Special Dry is specifically engineered for high-performance renovations and new builds where maximum thermal insulation and thick profiles are required.

CHARCTERISTICS

• 4-Fold Functionality: It provides four critical building functions in a single product: thermal insulation, wind tightness, temporary weather protection, and a direct substrate for render or cladding.
• Superior Thermal Efficiency: It offers better pure insulation performance than the denser Universal boards, helping to meet strict U-value targets with less bulk.
• Exceptional Summer Heat Protection: Despite being lighter than wet boards, its density of 140kg/m3 still provides high thermal mass. This creates a "decrement delay" that keeps the building interior cool during hot summer days.
• Precision Tongue & Groove: Featuring an engineered T&G profile on all four sides, it creates a wind-tight, interlocking layer that drastically reduces thermal bridging and eliminates the need for additional joint taping in many applications.
• Extended Weather Protection: Once installed, these boards can be exposed to the elements for up to 12 weeks on new build projects (or 4 weeks for renovations), allowing the internal work to proceed before the final roof or wall finish is applied.

APPLICATION

• Over-Rafter Insulation (Sarking): The ideal choice for roof renovations where rafters aren't deep enough for modern insulation standards. It sits on top of the rafters, wrapping the entire roof in a continuous thermal blanket.
• External Wall Sheathing: Used on timber frame or solid wood walls to provide a breathable, weather-resistant envelope that can be finished with timber cladding or a direct-applied render system.
• Passive House & Low Energy Builds: Frequently specified in high-performance projects due to its ability to virtually eliminate cold bridging at structural junctions.

CERTIFICATIONS