Fire Resilience

Flat roof fire protection – how to identify and mitigate the risks

Lisa Stephens, Product Manager – Building Envelope
Lisa Stephens, Product Manager – Building Envelope
December 1, 2022

It took Ocado over two years and £110m to rebuild its Andover warehouse when in February 2019, a factory-floor robot caught on fire, which quickly spread through the building.

Everyone inside was led to safety, but by the time the fire services arrived, the fire had already spread to the roof and nothing could be done – the building burned down after four days.

Industrial and manufacturing properties, such as the Ocado warehouse, are among the most fire-prone buildings due to their use, design and type of materials often used in roof construction. One might wonder, how can some of the UK’s most valuable buildings, which make up 10% of net wealth and support the employment of millions, also be at such high risk of fire? There are strict fire safety regulations to govern their construction and maintenance. But in some areas, the regulations are still open to interpretation, which can lead to significant risks.

For example, when the government introduced the ban on combustible materials in the new building regulations, the roof did not fall within the scope of the ban. As a result, the materials used in roof construction can vary greatly, and can be combustible.

Using combustible materials in flat roof construction is not worth the risk

The materials and cavities within roof spaces can cause fire to spread rapidly and extensively, making it much harder to contain. Combustible insulation can contribute to the fire load and provide a path for the fire to spread internally.

In a roof fire, it’s likely the building and its inventory – such as machinery and equipment – will be lost completely and have to be written off as business assets. In some cases, and dependent on backup protocols, losses can be irreversible, such as a fire in a data centre.

Aside from the unavoidable financial damages from commercial roof fires, the sustained damages to a building can also be significant. Even if the premises are recovered or rebuilt, the effect on the environment from fire effluent may cause additional health and safety hazards.

The role of the modern roof

Less land space has led to an evolution in the role of the roof, which has emerged as a valuable space that can be used for a variety of purposes.

Whether it’s for additional residential space or to house green projects and solar panels, roofs being seen only as storage areas is a thing of the past. These new uses of the roof are important for a building’s success and profitability – but they also leave the roof more vulnerable to fire, especially around equipment connection points that may not be sealed properly.

The role of the roof is expanding in ways that make flat roof fire protection more important than ever. The risks must be addressed, and specifying non-combustible materials early within the design phase may help to mitigate fire spread in the event of fire.

How to identify and protect against flat-roof fire risk

Aside from knowing the common risks a flat roof is exposed to, like arson, hot works and equipment failure, building managers should have thorough risk assessments and control measures specific to their building.

Some non-residential properties use thermal image cameras and monitoring software, while others use firebreaks where appropriate.

Stone wool is an example of non-combustible flat roof insulation that neither contributes to fire growth nor emits significant toxic smoke in the event of a fire. Through its inherent properties, it does not provide a means for fire to spread. Using stone wool in the design of the flat roof can support the passive fire protection strategy of the whole building while at the same time providing proven thermal and acoustic benefits. Find out more about specific applications, such as tapered roofs, in our article on Compliance and Tapered Falls.

Architects, designers and specifiers can upskill to better manage fire risk

Buildings have heritage and history, and for many, they carry enormous social and sentimental value. It’s where communities grow and thrive, where people meet, and where life-defining experiences and decisions are made. Protecting them means protecting the future – and our CPD on managing fire risk in roofs gives building professionals key advice and insights into best practice measures and useful resources.

Article History

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

Current version: 1

First published: 1/12/2022