Guiding you through Rainscreen Cladding and BS8414 full-scale fire testing

At Starfish Construction Group, our design expertise and innovative use of rainscreen cladding solutions throughout the UK's property sector not only enhances a building's aesthetics but is a critical safety component. Rainscreen cladding applications have made a considerable rise over the last few years, and the value they add to properties is a vital element of a building’s infrastructure.

The evolution of rainscreen cladding is exciting and breathes new life into ageing properties or adds a compelling visual finish to new build projects. However, cladding safety must be at forefront of every installation. It’s true that rainscreen cladding can add substantial value to a property, but it’s critical that property owners and investors do not fall foul of the potential of having a building that could potentially have the issue of having a zero-rated value, due to non-legislative fire safety testing and certification, placed on the property.

In this insight article, Joe McCabe, National General Manager, Building Envelope Division at Starfish Construction, explains the considerations when developing a rainscreen cladding application project. Joe also brings us up to date with the current testing programme where Starfish Construction is playing a pivotal role.

On rainscreen cladding projects, it is essential to select the right materials from design through to installation. Style, colour and texture play a vital role in creating a facade that adds visual appeal to the surrounding area. Architects, planners and of course, rainscreen cladding designers continually assess the best solutions for a wide range of properties. Fire testing is an essential element to that mix also, providing the critical safety information for any rainscreen cladding project.

As part of Starfish Construction’s £15 million Professional Indemnity Insurance, the safety of the materials we use is equally as important as the safety of our site, operatives and the public.

Your project in safe hands

Before starting to design, fire safety has to be the first thought and solution to every rainscreen cladding project.

Recently, we were engaged in constructing full-scale Fire Test Rigs, which are involved in BS8414 full-scale test to BS135.

I recently attended the site and witnessed a test in action. I must say that the levels of testing provide an exceptional understanding of the materials and how they will act under certain circumstances. It also underlines why, as an industry, robust testing is critical.

The testing ensures that one of our current projects meets the enhanced building regulations put in place following the Grenfell Tower tragedy. As a company, we welcome the updates to these regulations.

The property stakeholder we are supporting requested us to perform full-scale testing, which demonstrates their desire to deliver safe and sustainable buildings.

Our in-house design department applied the linear route of choosing non-combustible or limited combustibility A1 or A2 solution. This choice included the encapsulation of any exposed Ethylene Propylene Diene Monomer (EPDM). The Grenfell Inquiry demonstrated that EPDM weatherproof seals were a combustible material. Therefore, the encapsulation process significantly improves the fire resistance of the material.

Creating the test rig replicated the exact construction process of the completed building. Over three individual tests, we collated data to reflect the reaction of the full build-up of every component within the rainscreen cladding zones on the project. The test facility we developed included:

Internal Layer

  • A silicate-based cementitious board with a classification of A1.
  • Cortex breather membrane classification A2.
  • Envelope helping hand carrier system classification A2.
  • Mineral Wool Duo slab insulation classification A1.
  • Siderise Horizontal fire barriers RH25G 120/60.
  • Siderise Vertical fire barriers RVG 120/120.

External

  • A combination of 3mm PPC powder-coated aluminium cassette & face fixed system which has an A2 S1 D0 rating.

The precision testing performed under the strict guidance of the on-site examination manager would ensure impartiality and safety.

As the carcase of the wooden woven box, allocated within the safe zone, was ignited, it became fully engulfed in flames within seconds. It was an extraordinary sight to experience the fire, as the flames grew within the combustion chamber and rolled around as if in slow motion.

The flames quickly found a path out of the chamber, like running water onto the face of the external rainscreen. The heat radiation was overwhelming, and you could feel the heat through your safety clothing from 30 yards away.

Within 10 minutes, the paint surface on the aluminium panels started to disintegrate, showing the bare substrate. Within a further 5 minutes, the flashing details around the chamber began to break down, and the aluminium appeared to deteriorate and evaporated within the flames.

Around 20 minutes into the test, it hit a peak of 650 degrees Celsius. The panels directly in front of the chamber now disappeared up to the 1st fire break. Surprisingly after witnessing such an intense fire, the deterioration to the panels stopped in this location.

The Duo-slab insulation and fire barriers stayed in place, and there were no notable effects of fire on the face of the duo slab or the stainless-steel fixings that held the slab to the cementitious boarding. For me, this was an explicit endorsement of our values ‘Diagnose, Design and Deliver’ process and proved our approach as a safe and sustainable way forward. When you combine this process with testing and professional to all aspects of the building, we ultimately are driven by a safety-first approach to projects.

For facts and guidance to make informed decision choices for your rainscreen cladding project, speak to our advisers. Our integrity and expertise will ensure you have a legislative approach to your projects.