Whichever route is chosen, compliance with the Building Regulations, including the requirements in Part B, is a legal requirement. It is therefore key to identify a robust and defensible route to compliance from early stages of a project.
Therefore, in a recent publication 7 the Collaborative Reporting for Safer Structures (CROSS) expert panel has reinforced that: “Those with responsibility for meeting the requirements of the regulations will need to consider for themselves whether following the guidance in the Approved Documents is likely to meet those requirements in the particular circumstances of their case.”
ADOPTING DESIGN GUIDANCE
For common building situations, the fire safety requirements of the Building Regulations can be satisfied by following the relevant guidance in Approved Documents or similar standards – for commercial buildings this is typically through Approved Document B or BS 99996. Approved Document B and BS 9999 contain a collection of recommendations that, if applied in their entirety and adopted in the design of common building situations, result in a building design that can satisfy Part B of Schedule 1 of the Building Regulations. The restriction in scope of applicability, ie to common building situations, intends to ensure that the series of recommendations align with the implicit assumptions regarding how fires may develop, how elements of construction might perform, how occupants might react, etc. In facilitating the issue of Approved Documents, the Building Act states that, where applied within their intended remits, proof of compliance with such a document may be relied on as tending towards negative liability. Conversely, a failure to comply with a relevant approved document may be relied upon as tending to establish liability. The Approved Documents do not define what constitutes a common building situation. However, some indications are given in the introduction of Approved Document B as to situations that might be uncommon. These include: – Difficult ground conditions. – Buildings with unusual occupancies or high levels of complexity. – Very large or very tall buildings. – Large timber buildings. – Some buildings that incorporate modern construction methods.
Further, the expert panel goes on to conclude that:
“….the use of CLT in multi-storey buildings is not a “common building situation” as defined in the Approved Documents as they are currently published.” The conclusion by CROSS primarily relates to concerns about the implications of the structure’s involvement as a source of fuel and how this could lead to incompatibilities with underlying assumptions made in arriving at the recommendations in Approved Document B. This has subsequently been supported by specific FAQ8 guidance being published by the Department for Levelling Up, Housing and Communities, on the topic of combustible structures, which states: “Following the guidance in Approved Document B, including the minimum fire resistance periods and the standard test methods, may not be sufficient to meet the requirements of the building regulations, particularly in cases where the consequences of fire spread, and fire induced structural failure are more significant.” In extension, the same conclusion would hold for all forms of combustible structural solution and is not limited to mass timber. Furthermore, similar compliance tools, such as BS 9999 could also be considered subject to the same limitations / scope of applicability.
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