External cladding is an important part of building design and construction. It performs several vital functions including weather resistance, noise dampening, thermal insulation and aesthetics. The choice of materials is vast and each has its pros and cons. Many different factors, including the size, structure, purpose, budget and location of the building all factor into your cladding choice. But safety must sit at the very top of the list. Following the tragic Grenfell Tower fire in London, UK, in 2017, fire safety has become of particular importance when choosing cladding material. As the UK Government continues to drive activity to remove combustible cladding from high rise buildings, architects and construction firms are under increased pressure to ensure that new buildings conform to more stringent fire safety requirements.
What is cladding and why is it used?
External cladding forms the outer, protective layer of a building and provides a myriad of functions:
- Weather-proofing – working to direct rain or wind away from the building structure and prevent damp or damage
- Insulation – most cladding forms an insulating barrier of air between it and the external walls – this insulation provides thermal protection and noise dampening function
- Aesthetics –a range of different visual effects can be achieved with cladding material
- Fire protection – certain cladding can be used to reduce the spread of fire
Depending on the size of the building, its purpose, the client’s budget and the location of the building, a wide range of cladding materials are available. Typical domestic cladding might include timber, uPVC cladding or fibre cement weatherboards. Timber is a more traditional material and although it provides protection against weathering, it does require maintenance and can be susceptible to damp or rot. Modern uPVC boards can provide a similar appearance to wood but with greater colour options and longer-lasting, low maintenance qualities. Fibre cement versions now provide similar benefits with added increased fire resistance.
Larger buildings, such as offices, factories, hotels and tower blocks tend to feature sheet-style cladding for easier installation and maintenance. Metal cladding, such as steel, aluminium or zinc are popular choices, as are composite options, with a core material sandwiched between two thin metal sheets, usually aluminium. Glass fixed to a steel frame is often chosen for modern offices but other materials, such as wood, PVC and fibre cement weatherboards are also used in some applications.
As well as the functional capabilities, each cladding type will be considered along with the available budget, maintenance needs, building regulation requirements and the overall look of the building.
Safety first when it comes to cladding
There are several health and safety concerns when it comes to cladding. Installation usually involves working at height and if the cladding isn’t installed correctly, it can come loose and break away from the building, causing pieces to fall off or water ingress that can lead to damp.
But the biggest concern is around cladding fire safety. Some materials, such as bricks, fibre cement or steel, have high fire resistance but others, such as timber, plywood or certain composite materials, have poor resistance.
Avoiding combustible cladding
The most noted of these is aluminium composite materials (ACM) or ACM panels (ACP). ACM consists of thin aluminium sheets that sandwich a lightweight core, usually made from another metal, mineral compound, polyethylene or polyurethane. The cladding in place on Grenfell Tower was ACM with a polyethylene core. The investigation into the fire concluded that the combustible cladding acted as a source of fuel and was the principal reason why the fire spread so fast up, down and around the building.
The public enquiry into the fire resulted in a nationwide project to identify high-rise buildings (greater than 18m tall) that contain ACM cladding so that they can be tested for fire resistance. 456 buildings were identified as having unsafe, combustible ACM cladding. The latest audit report by the National Audit Office in June 2020 recorded that of these 456 buildings, 149 had been fully remediated, 140 were still being worked on and 167 had seen no remedial action. The Building Safety Programme, launched by the Ministry of Housing, Communities and Local Government (MHCLG) has banned combustible materials in new builds over 18m tall and is currently in consultation to reduce the limit to 11m. The current change regarding combustible cladding is now also part of the new Building Regulations.
Cladding fire safety with PlanRadar
Cladding should form a part of the fire safety assessment before any building is handed over, post-construction. By documenting the exact specifications of the cladding, its composition and its fire risk, building owners and operators can easily access important information. If regulations change in the future, if renovations are required or if the cladding needs to be recalled or replaced the documentation should be easily accessible and actionable.
Completing fire assessments is easy through the PlanRadar app, using pre-existing templates that can be adjusted for your specific project needs. Attach documents, testing results, images and other information about cladding directly to the building blueprint. As-built documentation can be collated during construction, providing simpler handover and ensuring no element is missed.
For more information on completing fire assessments and producing as-built documentation on PlanRadar, feel free to contact us.