Second BBA certificate awarded to Knauf Insulation's RainScreen Slab

By Knauf Insulation UK & Ireland
June 11, 2019

Knauf Insulation’s RainScreen Slab has received a second certificate from the British Board of Agrément (BBA), this time for use behind masonry.

The BBA certification applies to the use of RainScreen Slab as partial fill thermal insulation on conventional steel-frame walls with a masonry outer leaf. It is suitable for use on both domestic and non-domestic buildings.

The new certification comes just two months after RainScreen Slab was certified by the BBA for use in high rise residential applications. This followed the December 2018 update to approved Document B mandating the use of non-combustible materials achieving a Euroclass Reaction to Fire Classification of A1 or A2 s1-d0 in the external walls of certain buildings over 18m in height. RainScreen Slab has the best possible Euroclass Reaction to Fire classification of A1.

“This latest certification by the BBA demonstrates that RainScreen Slab is a highly versatile insulation solution,” said Luke Davies, Product Manager – Rock Mineral Wool at Knauf Insulation. “As well as being non-combustible, RainScreen Slab offers superior thermal performance making it the right choice for architects, specifiers and contractors.”

“BBA certification ensures customers specifying or installing RainScreen Slab can have absolute confidence in its quality and performance for buildings of any height or for any rainscreen application.”

RainScreen Slab has a thermal conductivity of 0.034W/mK. It offers superior robustness and durability, with a water repellent additive to preserve its integrity while exposed during construction. 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.

RainScreen Slab is optimised for ease of installation. The improved robustness of the product makes it easy to manoeuvre in place, and it is designed to adapt to minor imperfections in the substrate. It is manufactured in the UK at Knauf Insulation’s Queensferry plant using ECOSE® Technology, its patented bio-based binder. This makes the manufacture of its products 70% less energy-intensive compared to mineral wool products made using traditional formaldehyde-based binders.

For more information on RainScreen Slab, visit

To discuss your rainscreen project with the Knauf Insulation Specification Team call 01744 766 866.