Fire Resilience
Renovation Refurb and Retrofit
Standards & Regulations

A practical guide to reducing the economic impact of fire

Lisa Stephens, Product Manager – Building Envelope
Lisa Stephens, Product Manager – Building Envelope
December 8, 2022

The real economic impact of fire in roofs - and how to reduce the risks

Every industry has its defining moments. Whether it’s a global challenge, a groundbreaking innovation, or a change in regulations, some events completely reshape how a sector works. GDPR was the catalyst for stricter information security and privacy. Healthcare, along with many other sectors, was completely transformed during the COVID-19 pandemic. And for construction, the Grenfell Tower fire in 2017 is often seen as a turning point – both in terms of legislation and attitudes toward fire safety.

After Grenfell, stricter building regulations were introduced, including a ban on using combustible materials in the external walls of relevant buildings over 18m[1]. But an increasingly important part of the building was not included in the ban – the fifth façade, more commonly known as the roof. 

Unlike fires in the cladding or elsewhere in the building, a fire in the roof can often lead to complete loss of the building – or a long period of disruption that some businesses may never fully recover from. This causes a wider human, social and economic impact that can seriously affect a local community.

Lisa Stephens, Product Manager - Building Envelope at ROCKWOOL UK, explains the causes of fire, the changes in regulations, and what building professionals can do to manage risk and protect communities.

In 2017/18, arson accounted for 50.5% of all callouts, according to the NFCC and fire rescue statistics.
NFCC and fire rescue statistics.

The real social and economic impact of fire in the roof

Although all roof constructions are susceptible to fire spread from within a building or nearby structures, flat roofs are at a greater risk of being the source of fire as they can easily be accessed both from the inside and outside. 

Deliberately setting fire is the most widespread cause and typically accounts for half of fire service call-outs in the UK,. In 2017/18, arson accounted for 50.5% of all callouts, according to the NFCC and fire rescue statistics. It’s a concern for all flat-roof buildings but schools are particularly vulnerable to arson, with some insurance reports revealing that 75% of school fires are ‘struck maliciously’. 

One such case was the St. Albans Primary School fire in Wednesfield. When arsonists gained access to a flat roof at the school, fire quickly spread across the roof leading to a severe blaze. And although the building didn’t collapse, the school was forced to close for weeks and its 177 students were relocated to local facilities, causing widespread disruption. 

When taking into account the added cost of job loss and the disruption to parents, staff, and support services, the real cost of school fire can be as high as £115 million in just one year, according to the Arson Prevention Bureau. And that’s not counting the long-lasting indirect and emotional impact on the people affected.

Flat roofs are often used in other public spaces such as hospitals, social hubs, places of worship – buildings that are the lifelines of our communities – and so having combustible elements in the roof insulation is a great risk.

That’s not to say the social impact of a roof fire in commercial buildings is any lesser. In the roof fire of Primark’s Belfast store, mentioned in our whitepaper, the shopping centre saw a massive (49%) drop in footfall, thousands of local workers were affected and public transport numbers never fully recovered.

Why are flat roofs at greater risk of fire – and the problem with regulating roofs

Aside from arson, the other common causes of fire in roofs are:

  • Hot works, such as grinding, welding, and torch-applied roofing, that take place on or near the roof
  • Localised fire spreading to the roof – from the inside or falling debris from an adjacent building
  • Plant equipment failure, such as solar panels, or in the case of Ocado, a faulty robot, which cost them £110 million and complete destruction of the facility

Confusion in the market regarding testing, standards, and legislation for fire performance adds to these issues. In Approved Document B, Test 4 of CEN/TS 1187:2012, says that the highest classification for measuring roof performance during external fire exposure is BROOF(t4). The standard associated with this test is BS EN13501-5.

The problem with this test is that it’s not designed to determine the combustibility of a material – it is not a measure of combustibility. Test 4 looks at the roof system as a whole rather than how its individual parts perform in real-world conditions. It only covers external exposure to fire – it doesn’t assess how fire penetrates from underneath the roof.

Some manufacturers are claiming their BS EN13501-5-rated products are non-combustible – but a Test 4 rating alone is not sufficient to indicate this. The only way an insulation product can be classed as non-combustible is to achieve a Euroclass rating of either A1 or A2-s1,d0. 

Ultimately, to ensure that the golden thread of accountability is maintained, it is contingent upon all building stakeholders to ensure that their contribution upholds key building regulation requirements. In this manner, it is best practice to specify and install non-combustible materials across a flat roof. 

How to reduce the risk of roof fire and avoid hidden socio-economic costs

The simplest way to tell whether a product is combustible or not is to look at its Euroclass rating. Non-combustible materials with a Euroclass rating of A1 / A2-s1, d0 are materials that will not contribute to fire growth nor emit significant toxic smoke. As such, they’re the only viable option for properly managing fire risk. Choosing non-combustible roof insulation can reduce the potential consequences of a fire and secure a higher degree of protection if one occurs. 

Specifying non-combustible roof insulation from the start is not only prudence – it’s best practice. In an ever-evolving regulatory landscape and with changing client demands, it’s up to innovative market leaders to set the standard for quality. And it’s up to contractors to go beyond the bare minimum requirements. That way, we can all live, work and socialise in safer buildings.

Products that don’t contribute to a fire, such as stone wool, have proved their performance in the real world. Incorporating non-combustible building materials can provide meaningful benefits to businesses in the event of a fire. It can reduce the risk of severe damages and support businesses to get back into action quickly. 

So, act now and specify non-combustible materials from the design stage – it can be much harder to retrofit. And check out our whitepaper on managing risk in the fifth façade to deepen your knowledge and expertise.

Article History

Our experts continually review and update our articles when legislation changes or new information becomes available. 

Current version: 1

First published: 12/08/2022