BBA awards first ever certification for rainscreen double layering and below DPCs to Knauf Insulation

By Knauf Insulation UK & Ireland
June 17, 2021

Knauf Insulation’s Rocksilk® RainScreen Slab has earned the industry’s first BBA certification for double layering and for use below the damp proof course (DPC), making it certified for the broadest range of build-ups of any rainscreen solution on the market.

“We know how much architects and contractors value the peace of mind that comes from BBA certification,” said Luke Davies, Product Manager at Knauf Insulation. “Our Rocksilk® RainScreen Slab is already certified for use in steel frames and behind masonry. Adding these applications and installation methods means customers can rely on Rocksilk® RainScreen Slab to provide a robust and durable solution, certified for all common rainscreen build-ups.”

Rocksilk® RainScreen Slab is a non-combustible Rock Mineral Wool slab with Euroclass A1 reaction to fire classification, which means it complies with the strictest requirements of Approved Document B for dwelling buildings over 18m tall. It is available in the widest range of thicknesses up to 250mm, with a thermal conductivity of 0.034W/mK.

Rocksilk® RainScreen Slab can be used in situations where it bridges the DPCs of the inner and outer leaf because it does not absorb water by capillary action. It is manufactured with a water repellent additive which also preserves its integrity while exposed during construction, and it has been wind load tested by the Building Research Establishment to a maximum design pressure of 3,600Pa or 76m/s – the equivalent of a category 5 hurricane. The BBA certification also covers timber frame applications with a masonry outer leaf, and on reinforced concrete substrates.

Rocksilk® RainScreen Slab is optimised for ease of installation. The improved robustness of the product makes it easy to manoeuvre in place, while still being able to adapt to minor imperfections in the substrate. The product is supported with extensive installation guides, which cover the double layering and below DPC applications.

Rocksilk® RainScreen Slab is manufactured using ECOSE® Technology, Knauf Insulation’s unique bio-based binder, which contains no added formaldehyde or phenol. Mineral Wool insulation made with ECOSE® Technology is more environmentally friendly than insulation made using traditional oil-based binders. It is also soft to touch, easy to handle, and it generates low levels of dust and VOCs.

For more information on Rocksilk® RainScreen Slab, visit

To speak with a member of the Knauf Insulation Technical Support Team about your project call 01744 766 666.