Fire safety is of paramount importance in the UK, particularly after the Grenfell tragedy of 2017. In response, legislation and guidance has continued evolving to provide adequate safety measures. The tragedy proved to be a significant moment for the high-rise building industry. The use of non-combustible materials in buildings taller than 18m is an industry-wide practice as a result. Whilst this is commendable, the various legislations continue to disregard flat roofs and flat roof fire safety. Flat roofs are a prominent feature in many UK buildings, particularly in urban settings where space is limited. They offer numerous benefits, such as rooftop gardens and solar panel installations, but also pose unique fire safety challenges.

What is a flat roof?

A flat roof is a type of roof that is almost level, with a slight pitch to allow for water drainage. Unlike pitched roofs, flat roofs have a horizontal or nearly horizontal surface. They are commonly found in commercial buildings, industrial complexes, and modern residential designs. Flat roofs offer practical benefits, such as space for HVAC systems, rooftop gardens, or solar panels. However, they require specific materials and construction techniques to ensure proper drainage and avoid water pooling, which can lead to leaks and structural damage.

Fire safety is a critical consideration in building design, with flat roofs posing particular risks. The flat surface can allow fires to spread rapidly across the roof, and if not properly constructed or maintained, flat roofs can become weak points in a building’s fire resistance.

Building Regulations for flat roof fire safety

Fire safety for buildings, including those with flat roofs, is primarily governed by the Building Regulations 2010. The relevant parts of these regulations include:

Part B: Fire Safety

Part B of the Building Regulations focuses on fire safety, outlining requirements to ensure buildings can be safely evacuated during a fire and that the spread of fire and smoke is controlled. For flat roofs, important considerations include:

• Roof Coverings: Regulation B4 mandates that roof coverings must resist the spread of fire. Materials used should meet standards specified in Approved Document B, which outlines the fire resistance properties required for roofing materials.
• Compartmentation: To prevent fire spread, buildings must have fire-resistant barriers or walls that compartmentalise different sections, including the roof.
• Access and Facilities for Firefighters: It is crucial to provide access points, such as roof hatches, that allow firefighters to reach the roof quickly during an emergency.

Approved Document B

Approved Document B provides detailed guidance on complying with Part B of the Building Regulations. It specifies fire-resistant materials and design strategies to enhance fire safety for flat roofs. Key points include:

• Material Standards: Roof coverings must meet specific fire resistance standards, classified under European or British standards (e.g., BS 476).
• Fire Stops and Barriers: Incorporating fire stops and barriers in flat roofs is essential to prevent the spread of fire across the roof surface.

The Building Safety Act 2022

The Building Safety Act 2022, introduced in response to the Grenfell Tower disaster, brings significant reforms to enhance the safety of buildings across the UK. Here are the key aspects of the Act relevant to flat roofs:

Provisions of the Building Safety Act 2022

1. Higher-Risk Buildings:
   • The Act defines “higher-risk buildings” as those at least 18 metres in height or having at least seven storeys. Stringent safety measures are required for these buildings, including constructing and maintaining flat roofs to ensure they do not compromise overall fire safety​ (CIOB)​​ (Home)​.
2. Fire Safety and Compliance:
   • The Act integrates with the Fire Safety Act 2021, ensuring that fire safety assessments include all building parts, such as flat roofs. This means Responsible Persons must assess and manage fire risks associated with flat roofs in multi-occupied residential buildings​ (CIOB)​.
3. Regulatory Oversight:
   • The establishment of the Building Safety Regulator aims to oversee the implementation of safety standards, including those pertaining to flat roofs. This body ensures compliance and enforces safety measures in higher-risk buildings​ (GOV.UK)​.
4. Duty Holders and Accountability:
   • The Act introduces clear roles and responsibilities for duty holders, such as the Principal Designer and Principal Contractor, to manage safety risks during the design, construction, and occupation phases. This includes ensuring flat roofs are built and maintained to meet safety standards​ (CIOB)​.
5. Protections for Leaseholders:
   • The Act protects leaseholders from bearing the costs of remediating historical safety defects. This includes costs associated with upgrading or repairing flat roofs to meet current safety standards​ (CIOB)​.