Rockpanel’s Mark Snowden outlines the benefits of ventilated cladding buildups, in terms of the affect on fire safety performance in the wake of Grenfell Tower, as well as how such systems can benefit internal environmental quality in projects
The Grenfell Tower fire in 2017 marked a defining moment in the public’s consciousness regarding the fire safety of materials and systems used in the external cladding of new and renovated high-rise structures. Also brought into stark focus were issues concerning compliance and interpretation of fire regs and Building Regulations and how they impact on the materials originally specified for a project compared to what was, in reality, used.
In England, changes to fire regulations regarding residential and ‘institutional’ buildings over 18 metres made it mandatory that all components in the external wall meet or exceed EN13501 Class A2-s1,d0, with guidance that those of 11 metres also adhere to the same specification. Furthermore, in Scotland, recent changes in legislation state that only non-combustible systems, using materials classified as A1 and A2-s1, d0, are permitted on high-rise domestic and select high-risk buildings (including hospitals, care homes and entertainment complexes) over 11 metres.
Ventilated facades
A ventilated facade is a construction with an air gap between the insulation and the cladding. This gap is open at the top and bottom of the facade and the cladding panels have small open joints between them. A ventilated facade can be viewed as a raincoat: it protects a building against the elements while at the same time helping maintain a healthy indoor climate. This is why the building technique of ventilated facades is often referred to as rainscreen cladding.
This type of external cladding offers many advantages, both in new build and retrofit refurbishment projects. A ventilated facade is lighter and quicker to install than other options, leading to savings in construction costs. Individual panels can be demounted easily for maintenance and the whole facade can be replaced with the least inconvenience to the building’s inhabitants.
Once in place, a ventilated facade reduces the direct solar impact on the building, resulting in a healthier indoor climate. It also offers thermal insulation, which contributes to energy efficiency and acts to reduce the impact of exterior noise on those within. Ventilated cladding also affords architects and specifiers opportunities to use colour and other surface designs to create facades not achievable with other alternatives.
The Euroclass system
Euroclass represents the most comprehensive and up-to-date standards system regarding reaction to fire. It compares ignitability, flame spread,
heat release, smoke production, and propensity for producing flaming droplets/particles etc. Within this system each classification means that for a product tested within a certain end-use situation, specific parameters are achieved.
For example, with relevance to the A2 rating, all of the tests for previous classification levels are completed, plus a test for the calorific content of the product. For instance, a classification of A2- s1,d0 means that a kit (a kit represents the collective parts of a tested system) is tested and been assessed as having a very limited calorific content (A2), a smoke propagation which is low or non-existent (s1) and no spread of droplets in the first 10 minutes of the fire (d0).
Considering the system holistically
In order to be confident that a facade adheres to the highest fire safety performance, it is vital to view the characteristics of its construction as a whole – from panels and sub-frame, through to the insulation used and the design of cavity compartmentation, fire barriers, fixings and all other components.
The images shown here are a selection of projects where Rockpanel non-combustible ventilated facades have been used. Aurum comprises 52 luxury apartments. Here a mixture of reflective gunmetal and gold facades were installed throughout its balconied, curved and faceted exterior.
Facades were installed in three distinct styles at Merry Hill, one of the larger retail destinations in the UK. Gold and titanium colour options create pyramids reflecting light and shadow, transforming throughout the day, while white and grey aluminium designs produce 3D effects. Also used were the striking colour changing characteristics of Chameleon – forming flowing waves of purple, green and blue.
Non-combustible facades were installed at the Station Medical Centre to add low maintenance, organic warmth and visual impact while avoiding the maintenance and deterioration issues associated with the ‘real thing.’
As a final example, non-combustible facades have been used to great effect in the complete recladding of three 1960s residential blocks, delivering a future proof transformation for the 186 homes within. A mixture of inherent fire safety and true matching of the replaced veneer HPL panels simplified the planning process.
Mark Snowden is country manager for UK at Rockpanel