ROCKWOOL Releases Technical Bulletin Providing Compliance Guidance for Insulated Upstand Boards

Will Wigfield, Product Manager at insulation manufacturer, ROCKWOOL UK, outlines the company’s latest roofing industry guidance, and details the background to its introduction.

Will Wigfield, ROCKWOOL UK Product Manager

AT ROCKWOOL, we have released a technical bulletin to provide guidance to roofing specifiers and contractors on the use of bonded construction materials, such as insulated upstand boards, and the finished product’s subsequent Euroclass reaction-to-fire rating.

Following the Grenfell disaster, a ban on combustible materials in the external walls of relevant buildings over 18m came into force in 2018. The ban reinforced the importance of non-combustibility and regulatory compliance in all areas of building construction.

Construction elements attached to the façade – such as upstands, balconies and terraces – fall within the scope of this ban. However, to develop specific solutions for these applications, some manufacturers have adopted techniques that include the bonding of insulation materials to create a composite board. This raises the potential for an inaccurate reaction-to-fire rating to be claimed on the finished product.

In response, ROCKWOOL has written a technical bulletin to give advice on the use of these composite products, and the potential impact of these on a building’s compliance with both Approved Document B (ADB) and the combustible ban (the need to achieve Euroclass A2-s1, d0 or better).

About Euroclass

The simplest way to determine the combustibility of a building product is by checking its Euroclass reaction-to-fire rating. A product’s Euroclass rating factors a comprehensive set of characteristics. These include ignitability, flame spread, heat release, smoke production and propensity for producing flaming droplets and particles.

Only products achieving classifications ‘A1’ and ‘A2-s1, d0’ can be used where the combustible ban applies.

Euroclass Classifications for Bonded Insulation Materials

Put simply, we’re seeing assumptions within the industry that bonding two Euroclass A1 rated materials together results in a composite A1 product, which isn’t always the case. Upstand boards for parapet walls are one of the products that fall within the ban which are often formed of two bonded insulation materials – a facing board and an insulation board.

It is critical to understand that when two materials are bonded, even if both are rated Euroclass A1 independently, the resulting composite product will not necessarily achieve Euroclass A1 status – or even A2-s1, d0.

This is because the organic content in the adhesive used to bond materials adversely affects the finished product’s reaction-to-fire rating, potentially resulting in a combustible Euroclass rating of B or lower. Achieving a non-combustible rating for these products requires the adhesive to be applied in a factory-controlled and precisely-calibrated manner.

For composite products, independent test evidence is required for the finished product to demonstrate compliance with Approved Document B and the combustible ban. In some cases, a bonded composite product may meet these requirements. However, responsible architects, specifiers and contractors should always request evidence of the reaction to fire classification EN13501-1 from the manufacturer to prove this.

It’s important that we support the industry to understand the importance of specifying and working with products that meet stringent safety ratings. We hope that adding this technical bulletin to our suite of support resources will give valuable advice to a wide range of audiences.

A Tested Bonded Solution

ROCKWOOL HARDROCK UB34 is a non-combustible insulation solution designed specifically for parapet walls and upstands on flat roofs. It comprises of a dense 50mm slab of ROCKWOOL stone wool insulation bonded to a rigid 6mm fibre cement board, and is suitable for use on buildings over 11 metres that are affected by the ban on combustible materials.

The product is impact and weather resistant, and ROCKWOOL has ensured that HARDROCK UB34 is tested as a finished composite product, and it has proven to achieve Euroclass A2-s1, d0.

HARDROCK UB34 is manufactured from cement fibre board and a ROCKWOOL stone wool insulation slab that has a thermal conductivity of 0.034 W/mK to reduce thermal bridging. The board is compatible with a range of flat roof systems, including single-ply and inverted.

UB34 helps specifiers and contractors mitigate fire risk by providing a durable, non-combustible insulation solution compliant with the latest guidance and regulations for buildings over 11m. It’s a purpose designed solution which is easy to install, and its stone wool core provides an excellent thermal performance.

More information about ROCKWOOL HARDROCK UB34 can be found here, and its reaction-to-fire certification is available on request.

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