Over the past few years, questions have been raised about the risk of fires in tall buildings. Following the Grenfell Tower fire, a decision was taken to ban combustible materials in the cladding of some buildings over 18m in height.
With this change to Approved Document 7 coming into force on 21 December 2018, what impact has this change had on how we design and construct tall buildings? This feature looks at some of the key considerations when designing tall buildings and how products – such as non-combustible cavity trays – have evolved to meet this new requirement.
When it comes to designing high-rise buildings, fire safety is a priority. Height is an important factor in fire safety as escaping from tall buildings is more complicated – it takes more time compared to a single-family house with only one floor and they are home to multiple inhabitants. The ban on combustible materials on some buildings over 18m has enabled a route to creating fire-safe buildings and the management of risk. In addition, new planning requirements for high-rise residential buildings, referred to as Planning Gateway One, came into force on 1 August 2021 and require fire safety to be considered at the earliest stages of planning.
These new requirements come in the wake of the Grenfell tragedy and Dame Judith Hackitt’s Independent Review of Building Regulations and Fire Safety. Her report highlighted the need to transform the building safety regime and recommended minimum requirements around fire safety be addressed before planning permission is granted.
Change in culture
The Grenfell tragedy focused attention on fire safety, from accountability to industry competence and the use of critical products. It’s why fire-safe design clearly should not be an afterthought with Planning Gateway One; the first of a series of ‘gateway points’, requiring high-rise developments to consider fire safety at the earliest stages of planning. This is intended to result in schemes that fully integrate thinking on fire safety. In short, high-rise developments will need to demonstrate they have been designed with fire safety in mind before planning permission is granted.
While these planning reforms are needed post-Grenfell, it’s a shame it took a tragedy such as Grenfell to force a fire strategy into early design thinking. Surely, this should form part of early discussions and be essential for all building types, not just high-rise residential? Although not currently in scope, it is expected that hotels and care homes will at some point form part of the discussion. Fire protection is essential for all building types if we are to create a resilient built environment.
In response to these changes, and the ban on combustible materials in some buildings over 18m in height, manufacturers have been forced to look at whether or not their existing products conform to new regulations. This has seen many being forced to change their products or move away from the high-rise market altogether. It has also provided an opportunity for innovation, with manufacturers focused on developing products with improved fire resistance and products that ensure consistent installation.
This innovation has created a range of new products and solutions that are specifically designed to meet and exceed the regulatory requirements. The development of a unique and commercially viable, rapid-build, non-combustible cavity tray that is simple to understand, easy to install and will meet the needs of insurers, warranty providers, developers and installers is one such example. These external cavity-wall solutions have been developed to meet both building regulations and issues with existing cavity trays whilst providing the complete non-combustible solution for the external cavity.
The non-combustible cavity tray is self-supporting and independent of the inner leaf and so does not create a thermal bridge and leaves zero possibility for differential movement. It is A1 fire rated, topped off with a keyed surface area to eliminate slip plane, making it the easiest and most efficient system to install.
By simply asking the right questions and listening, this solution has been created to eliminate one of the main reasons for product failure. Designed and built for best practice on site, it also meets the many other requirements that the industry requires, offering architects, housebuilders and contractors a risk-free, future-proofed option for buildings over 18m.
Ensuring safety is not just about choosing the right materials. There needs to be a collective responsibility towards fire safety, with architects and building designers engaging with manufacturers at the earliest stages of a project to ensure the most appropriate systems are in place.
The introduction of Planning Gateway One is welcomed but high-rise residential is just the starting point and we see this important step included in other building types. These are all essential buildings that must be fire safe to protect life as well as property.
All buildings must be robust, resilient and safe and this starts with the correct specification of materials. The target for product development should not be the minimum allowable standard, as this does not allow for any ‘on-site tolerances’. If a system is designed to achieve the minimum allowable standard and then encounters conditions on-site that further challenge its performance, it can easily drop below the minimum required standard. This results in a return to the ‘gap’ between what has been designed and what has been built, which has dominated the headlines in the past few years.
The use of modern building materials and techniques gives rise to many of these hidden challenges that have to be accommodated, so that buildings not only look great and work well but are also safe both now and in the future.
For more information, go to www.keyfix.com