Recent site fires have drawn attention to the hidden danger of incomplete roof systems, where exposed insulation and unfinished layers can greatly increase the potential for fire spread during construction.
Across the construction sector, several incidents have shown how combustible insulation materials such as extruded polystyrene (XPS) can present serious hazards when left exposed or unfixed on partially completed roofs. Although modern insulation boards often contain fire-retardant additives, they can still burn rapidly once ignited, allowing flames to move freely across the surface until the material is consumed or extinguished.
This vulnerability is not limited to polystyrene. Any combustible element, from adhesives to primers, can contribute to the fire load when it has not yet been fully encapsulated within the complete roof system. The key message for contractors and designers is simple: an incomplete roof behaves very differently from a finished one.
The Role of Design and Specification
Effective fire prevention begins at the design stage. Designers and specifiers are responsible for assessing the combustibility of individual materials and how they interact during different stages of construction. While it may not always be possible to substitute non-combustible components, it is essential to carry out a comprehensive design risk assessment that identifies how and when combustible materials will be protected.
Early encapsulation of insulation and other combustible elements should be planned into the construction sequence wherever possible. This ensures that the roof achieves its intended fire performance sooner, rather than being left exposed for long periods.
Designers must also provide clear information about Euroclass fire classifications, installation sequences, and storage or handling requirements. This information needs to reach contractors and site managers in time for them to apply the correct controls on site.
Managing Fire Risk On Site
Once construction is underway, the focus shifts to preventing ignition and controlling fire growth. Good site management plays a vital role in keeping materials safe and reducing overall fire risk.
Key precautions include:
- Limiting the amount of insulation and other combustible materials stored on site through just-in-time delivery.
- Keeping only what is needed for the current shift on the working area, with unused materials returned to storage at the end of the day.
- Storing products safely, ideally under flame-retardant sheeting and away from any ignition sources.
- Coordinating with other trades, since overlapping activities may increase the total fire load.
- Providing workers with clear information and supervision, so that everyone understands the site-specific fire precautions.
Many projects involve multiple duty holders, particularly refurbishment work or part-occupied buildings. Cooperation between principal contractors, building owners, and managing agents is essential to ensure that consistent fire controls are maintained throughout the project.
Fire Planning and Emergency Procedures
Even with robust prevention measures, every project must prepare for the possibility of fire. General Fire Precautions (GFPs) should be in place from the start and reviewed regularly as the project progresses. Fire risk changes with each stage of the build, so procedures must adapt accordingly.
Each site’s fire risk assessment should guide an emergency plan that includes:
- How fire alarms will be raised and maintained.
- The location and maintenance of firefighting equipment.
- Identification of trained personnel authorised to use equipment.
- Safe evacuation routes from the roof and adjoining areas.
- Assembly points and procedures to confirm all workers are accounted for.
- Responsibilities for coordinating the response and contacting emergency services.
Contractors are also encouraged to prepare a fire information pack for the local fire service. This should include details of any stored insulation, gas cylinders, adhesives, or other flammable materials at roof level. Providing this information helps emergency crews assess risks more quickly and respond safely.
Supporting Resources and Best Practice
Several important publications offer additional guidance for those managing fire safety in roofing and construction:
These resources set out how to plan, manage and monitor fire safety from the earliest design stage through to completion, helping contractors ensure that combustible materials are handled responsibly throughout the build.
Communication and Cooperation Are Essential
Reducing the fire risk of incomplete roof systems depends on planning, communication and teamwork across all parties involved. Designers, contractors and building managers each play a role in ensuring that materials are correctly specified, stored and installed, and that everyone on site understands the emergency procedures in place.
The fire load of a roof under construction changes daily as materials are added, removed or encapsulated. Continuous review of fire precautions is therefore essential to keep risk at an acceptable level.
By embedding these principles into everyday working practice, the industry can reduce the likelihood of future incidents and help protect both workers and property.
Stay connected
Subscribe to receive the latest blog posts and offers from Allbase direct to your inbox.
