Fire safety design – considerations for building façades

The built environment sector provides the spaces where we live, work, learn and play – having an impact on us all. There will always be a natural focus on high levels of safety through the design and construction process. From safeguarding those who work in the construction industry through to keeping people safe in their homes and places of work after the buildings are constructed.

Buildings must be designed to provide an expected level of fire safety and minimise the risks from heat and smoke. Simply put, the primary objective of fire safety compliance is to limit the potential for harm to occupants or other key parties, such as the fire service.

However, there will – and should – not be a one-size-fits-all approach to ensuring fire safety within building design. It remains a consideration unique and bespoke to every project based on many project specifics including:

• Building usage and mass
• End-user requirements
• Building facilities
• Construction materials

The latest legislation and a large proportion of recent discussion on fire safety has been focused on tall residential buildings, notably those taller than 18 metres. Though it would be sensible to apply the most up-to-date guidance to buildings of any height where people live and sleep.

Approved Document B provides guidance on how building regulations can be met in common building situations, but it is important to remember that every project is unique and more complex, larger buildings will have more varied considerations.

BS 9999 takes a more holistic view, allowing for compensatory methods to be offset, considering items such as escape distances, escape door widths, Automatic Opening Vents (AOVs), smoke ventilation, firefighting stairs. This standard provides a risk-based structure that considers varying human factors, reflects the requirements of the Disability Discrimination Act regarding inclusive design principles and ensures the design of buildings is fit for the varying requirements of end-users.

Façade materials

We find that clients’ questions on building facades are often specific to the building in question, even down to individual panels, nuts and bolts and how they will perform under certain circumstances. Our knowledge is crucial to not only realising the key outcomes, but also reassuring clients (and other parties) that the bespoke solutions are of the highest levels of safety and compliance.

For building facades in particular, every single element within an external wall, from the cladding materials through to the inner plasterboard skin must meet Euroclass A1 non-combustible or A2 limited combustibility, unless exempt under Section 7 of Approved Document B (Fire Safety).

Materials selection is not just about how the finished product will look. One of the biggest things we must do as designers is to ensure compliance through our material checks. These checks make sure that they hold the necessary fire test certifications and adhere to the latest legislation considering health and safety, cleaning and maintenance, hard and soft body impact, and expected life span of the systems, along with many other performance checks.

Examination goes beyond testing the specific material in isolation. We must check if the materials have been tested alongside the proposed adjacent elements to understand how they will interact under different circumstances.

Existing buildings

Work on existing buildings largely falls into cladding remediation, with building and fire safety being the primary goal. There are two key considerations for such projects:

• Existing Building users / tenants
• Structure and materials

For remediation schemes, design teams must allow for building tolerances and permit a certain level of agility to respond to potentially unknown elements, which can be hidden behind the existing cladding materials.

It is possible that people will remain in their dwellings while work is carried out. In these cases, we have to consider the disruption ensuring the safety of the tenants at all times and ensuring the workmanship carried out is of the upmost quality.

Equally, the project team must examine what additional risks and potential nuisance the work itself poses to people remaining in their homes, how this is both managed and communicated to the residents, and what strategies will be put in place to mitigate.

New buildings

While there is the benefit of starting from scratch, building facades are an equally big consideration for new buildings. No existing tolerances or materials considerations means there is more design freedom than on remediation schemes.

Various building materials and shapes will create differing levels of complexity to any project. For example, a rectangular building with simple render is a very different scheme to a curved, metal-clad structure.

This whole process needs to be carried out with many active parties involved, including architects, fire engineers, façade-engineers, Main Building Contractors, subcontractors, and building control. As outlined in the Construction Playbook, ensuring early engagement of all the parties serves to set the wider project team on a smooth progression path to delivering the work in a truly collaborative manner.

Fire-stopping in buildings

The coordination of how materials interact is important, but of equal importance for fire safety design is how they are physically put together.

Joints formed between fire-separating elements such as compartment walls or floors should be fire-stopped to maintain continuity of resistance. Approved Document B describes a fire stop as ‘a seal provided to close an imperfection of fit or design tolerance between elements or components, to restrict the passage of fire and smoke’.

Façade design has onward implications for a building that will require additional fire safety measures to be incorporated into the overall design. This includes fire-stopping and other barrier methods to cut off the spread of smoke or fire, both of which require strong awareness of the technicalities and standards required to work to.

The integrity of fire-stopping must also be maintained through repairs and refurbishment works to ensure it remains effective.

Fire safety design - staying ahead

The topic of fire safety will remain a key one into the future, along with wider building safety standards covered by the Building Safety Act. We know that further legislation will be discussed and introduced that will have an impact on the way we design buildings.

It remains our job to ensure project teams have the agility to adapt to new guidance as it is released, but also crucially to advise clients of changing standards, giving them the faith that they are getting both the best possible and most compliant solutions for their schemes.

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