Navigating Discrepancies in Higher-Risk Building Definitions: Does A storey containing only rooftop gardens count as AN additional storey in A 7 storey residential building?
Recently, MDLR Architects submitted a query to the Ministry of Housing, Communities & Local Government querying an inconsistency in the definition of “higher-risk buildings” (HRBs) between The Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 and the Approved Document Part B.
The Key Question: Roof Gardens and Higher-Risk Classification
Our query centred around a specific MDLR project currently going through the planning process: A 7-storey residential building where the top floor which is above 18m comprises only communal rooftop gardens.
- The HRB Regulations 2023 and accompanying government guidance explicitly exclude rooftop gardens from counting as a storey when determining if a building is “higher-risk.”
- Approved Document Part B, however, only excludes storeys containing solely of plant rooms and machinery, which does not exempt rooftop gardens from being included in the calculation of building height or number of storeys for regulatory compliance.
This distinction has significant implications for whether a building is classified as an HRB and the technical requirements it must meet. Project’s fire consultant felt that the proposed building would be classed as HRB and should go through BSR Gateway process. We weren’t convinced and wanted to get to the bottom of the discrepancy.
The Ministry’s Response: Which Definition Takes Precedence?
The Ministry clarified that:
- For HRB Classification: The HRB Regulations 2023 take precedence. In this context, rooftop gardens are excluded when measuring the top storey for determining if a building qualifies as “Higher Risk Building – HRB”
- For Compliance with Building Regulations however the Approved Document Part B serves as practical guidance. While it aligns with regulatory compliance, it uses a different approach for measuring storeys, which includes rooftop gardens.
This dual framework underscores the need for careful consideration of both legislative definitions and technical compliance standards.
Practical Implications for Designers and Developers
For the project in question—a 7-storey residential building with rooftop gardens—this means:
- HRB Classification: The building would not be classed as a higher-risk building. Therefore, it would not need to undergo the Building Safety Regulator gateway process or future registration as an HRB.
- Building Regulations Compliance: The rooftop gardens are currently (unless Part B is updated in the future to align with the HRB definition) considered a storey under Approved Document Part B. Consequently:
- A firefighting lift and a second evacuation lift are required, as the building height exceeds 18m.
- A second staircase is mandatory if construction does not sufficiently progress by September 2026.
Broader Industry Implications
This discrepancy illustrates a broader challenge within the regulatory landscape. Misaligned definitions create complexity for professionals navigating project approvals and compliance. Architects, building control officers, and developers must account for potentially conflicting requirements, balancing compliance with efficiency.
Our Recommendations for Navigating This Complexity
- Early Engagement: Involve competent designers, building control and fire safety consultants early in the design process to ensure alignment with both HRB and Part B requirements.
- Regular Monitoring: Stay updated on legislative changes, particularly potential amendments to Approved Document Part B, to anticipate their impact on ongoing projects.
- Clear Documentation: Maintain comprehensive records of decisions and justifications when interpreting regulations, especially for complex or ambiguous cases.
MDLR Architects: Your Partner in Navigating Regulatory Challenges
At MDLR Architects, we are committed to helping our clients achieve their project goals while navigating the complexities of an evolving regulatory environment. Our expertise ensures your designs are both innovative and compliant, delivering value without compromise.
If you have questions about how current building safety regulations impact your project, get in touch with us. Let us help you turn regulatory challenges into opportunities for excellence in design.