BS 9991- An Alternative Approach to Compliance, Not an Alternative to Compliance

At BSB Engineering Services Ltd, we are often asked whether a building must comply with Approved Document B or whether BS 9991 can be adopted instead. The answer is more nuanced than many realise. This technical paper provides an overview of how BS 9991 sits within the UK Building Regulations framework and why understanding its proper application is important for designers, contractors and regulators alike.

There remains a common misconception within the construction industry that Approved Document B is “the Building Regulations” and that any departure from its guidance requires a relaxation or concession. In reality, this is not the case.

The Building Regulations set out the functional requirements that buildings must satisfy. In England, these legal requirements are contained within Schedule 1 of the Building Regulations. How those requirements are demonstrated is a matter for the design team, provided that an appropriate and robust compliance strategy is adopted.

Approved Document B is simply one recognised route to demonstrating compliance with Part B – Fire Safety. It is guidance, not legislation. Likewise, BS 9991 provides an alternative, risk-based and technically developed approach for residential buildings. Neither document replaces the Building Regulations themselves; both are methodologies for demonstrating compliance with them.

Where BS 9991 is adopted, it should not be viewed as a means of circumventing Approved Document B. Rather, it represents a different design philosophy. The standard considers building use, occupancy characteristics, fire safety measures and evacuation strategies in a more holistic manner than the prescriptive guidance typically found within Approved Document B.

One of the most important principles often overlooked is that BS 9991 is not intended to be used selectively. It should not become a “pick and mix” exercise whereby individual clauses are chosen simply because they are perceived to be more favourable than those contained within Approved Document B.

If a project’s fire strategy is based upon BS 9991, the standard should be applied consistently and considered as an integrated approach to fire safety design.

This distinction has practical implications for all members of the project team. Designers, contractors, Building Control Bodies and Principal Designers should understand that a building designed in accordance with BS 9991 is not necessarily more or less compliant than one designed in accordance with Approved Document B.

The question is not which document has been followed, but whether the proposed design demonstrably satisfies the functional requirements of the Building Regulations.

From an engineering perspective, BS 9991 often provides greater flexibility in certain areas of residential design. However, that flexibility is accompanied by an expectation that the wider provisions of the standard are fully understood and appropriately implemented.

A design cannot simply adopt the most beneficial elements of multiple guidance documents without technical justification. Where BS 9991 is selected as the compliance strategy, the wider intent and interrelationship of its provisions should be respected throughout the design process.

Compliance Is With the Building Regulations

Ultimately, compliance is achieved with the Building Regulations themselves, not with any single guidance document.

Approved Document B and BS 9991 are tools available to the industry to demonstrate that compliance. Both have their place, and both require competent application.

As fire safety professionals, we should encourage a greater understanding of the distinction between statutory requirements and technical guidance. Doing so leads to better informed design decisions, more robust fire strategies and, most importantly, safer buildings.

Conclusion

The industry benefits when guidance documents are properly understood and applied in the manner intended by their authors. BS 9991 should not be regarded as a shortcut or an alternative to compliance itself. It is an alternative route to demonstrating compliance with the Building Regulations when adopted appropriately and applied holistically.

Whether a project is designed in accordance with Approved Document B, BS 9991 or a suitably justified fire-engineered solution, the objective remains the same: achieving safe, compliant and well-considered building designs.

Technical Paper 002  prepared by Nygel Humphrey, Commercial Director, BSB Engineering Services Ltd.