Scottish Building Regulations: Fire Safety review and Compliance: Call for Evidence
Fire Safety - Compartmentation/external fire spread and the stay put strategy
Recommendation 7 from the Grenfell Tower Inquiry Phase 2 Report:
- New materials and methods of construction including practice of over-cladding existing buildings make the existence of effective compartmentation a questionable assumption recommend that the stay put policy be reconsidered when Approved Document B (Section 2 Fire) is revised.
The Inquiry Report made clear that a failure to maintain compartmentation when undertaking retrofit of the facades of the building was a significant contributory factor in the rapid spread of fire through the building. This recommendation raises a clear question on the effectiveness of fire compartmentation in retrofit projects.
The report noted the reliance building regulations place on effective compartmentation for control of the spread of fire and smoke and also that fire spread between compartments can occur even in correctly specified and constructed buildings due to fire clinging to the external surface of a building and entering through vulnerable elements such as windows. The overriding concern being that if the external walls of a high-rise residential building support the spread of fire to any significant degree, it is not viable to operate a stay put strategy safely.
Building regulations set standards for the effective compartmentation of buildings to limit the internal spread of fire. In Scotland this is referred to as ‘separation’ in domestic buildings and addresses the fire separation between individual dwellings in a larger building (Standard 2.2). This also extends to measures to prevent the spread of fire on the facade of a building under Standard 2.7. Buildings which are appropriately designed, constructed and maintained are considered to support the stay put strategy where this is a design objective.
It is therefore important for those delivering work to a building to understand what constitutes effective ‘compartmentation’ as one of several important measures that deliver a fire safe environment.
If considered in the context of newbuild, the contribution of all fire safety requirements set under regulation need to be considered to assess residual risks. In addition to passive measures (such as the requirement for external wall cladding systems for ‘relevant buildings’, including blocks of flats at a height of 11m or more, to be constructed from non-combustible material from June 2022), this includes the presence of automatic fire suppression systems in new flatted developments from 2021. Facilities to support response to an incident by the fire and rescue service are also provided such as vehicle access, water supplies, dry risers, evacuation alert systems and fire-fighting lifts in high rise blocks of flats.
The outcome should be that new materials and methods of construction and the practice of over-cladding existing buildings can be managed properly and effective compartmentation demonstrated. We recognise that residual risks may remain, and it is these that should inform a wider discussion on the management of buildings and the response to a fire incident whilst noting ‘evacuation on alert’ may have the potential to hinder fire-fighting operations (with occupants evacuating) and the possibility for residents to move into smoke filled common areas from otherwise relative safety within flats.
As part of the review of Section 2 (Fire), Scottish Government will explore whether the existing regime for guidance and compliance (design and site-based work) is effective in ensuring compartmentation is achieved/maintained in retrofit projects. This will include public and targeted consultation with appropriate stakeholders such as Scottish Fire and Rescue Service, local authority verifiers, designers and fire engineers, following this call for evidence.
Examples of potential areas for development may be:
- developing clear guidance on the fire safety elements and strategy for buildings, such as flatted blocks, where undertaking retrofit external wall cladding systems to help manage the practice and outcome
This is linked to recommendation 9 relating to fire strategy/fire safety design summary.