SWECO BUILDING STANDARDS GUIDANCE NOTE
Independent Sections Building Regulations
Introduction
This guidance note is aimed to assist Sweco Registered Building Inspectors (RBI) and Duty Holder Support in verifying the clients view that a section of a completed Higher Risk Building (HRB) is an Independent Section, in that it does not form part of or impact the Higher Risk section(s) of the overall building.
It is important that the RBI follows the principle that the client provides their documented view as to why the proposed work is independent for verification as part of the statutory process.
Duty Holder Support can use this guidance to inform advice given to clients on Independent Sections.
When a “new build” HRB is obtaining consent, it is considered as a whole and subject to the Gateway Process through the Building Safety Regulator (BSR). Often this will be irrespective of the fact that the single structure comprises of several sections that once complete will be considered independent, and separate buildings under the regulations. *
Depending upon use, an independent section may be non HRB. In these cases, future building work would not be controlled through the Gateway process. Non HRB Independent Sections would not need to be part of the HRB registration with the BSR.
*The Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023.
Guidance
Independent or Not
To be independent, sections of buildings must be constructed in accordance with Building Regulation B3, by way of fire resisting construction to form compartmentation/separation between sections.
If a section is designed and constructed completely separately with no “pedestrian” connection (doorway, archway or similar opening) to another section then, it should be relatively simple to confirm the client’s interpretation.
Access
Where the sections are connected by an “access” opening, it should be clearly established that this opening will only be used during an emergency or access for maintenance.
It would be expected the client outlines how the connections use is confined to emergency or access for maintenance purposes. As a minimum this would be through physical controls & management but may involve additional layers of management such as security, concierge and tenant co-operation.
Anything other than emergency or maintenance purposes creates inter-dependence of sections.
“Exceptional Use” is used to categorise emergency and maintenance use in the regulations. If the design team uses “exceptional use” to establish independence where an opening is used for something other than emergency or maintenance, great care should be taken in considering whether the rationale is appropriate.
Separation by an enclosed walkways or a section that does not have a residential unit
If two buildings are linked by an enclosed walkway, the walkway must have its own independent means of access and egress for the buildings to be considered independent.
The BSR has talked in terms of the existence of a “thoroughfare” between buildings, indicating they are not independent. This is a safe interpretation. However, the reverse is not true. Stating that two buildings are independent because an opening between them does not create a thoroughfare would not stand unless it was shown the opening was for emergency or maintenance use only.
Regulation 4(6) of The Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 allows Independence to be established where two sections are connected by another section, that does not have a residential unit within it. In our view a common corridor, lobby or stair cannot be considered a section, as it is not in the spirit of the regulations.
Sweco’s view is generally that where Independent Sections have access to but are separated by a section with no residential use, it is advisable that access controls are put in place to ensure that a thoroughfare is not created between the independent sections.
The exception to this would be hospitals where a whole estate of individual buildings may be connected by enclosed walkways.
NHS Estates Technical Bulletin (NETB) No. 2024/2 gives guidance on an understanding reached by NHS England with the BSR.
“13. For the purpose of bullet 2a and 2b, “access” means a doorway, archway or similar opening unless used for exceptional use, including emergency use or for the purpose of maintenance. The BSR has confirmed that by access they mean direct access into the next independent section. Therefore, where there are a number of structures in a row, it is only the adjacent independent sections that need to be considered in determining whether a structure is an independent section.
14. The BSR has advised NHS England that even when an HRB “building” contains multiple attached structures, it is only the structures that contain residential units that have to be registered. Connected buildings (including “hospital” buildings) have to be mentioned as part of the key building information. The registration asks for confirmation of connections, but the rest of the information provided (including lifts, fire doors, external wall materials, etc) only has to be provided for the residential structure, not other connected structures.”
Plant
Independent Sections can share plant rooms and if one of the sections served is an HRB then the plant room is an HRB. To maintain independence, service runs passing between sections must comply with B3 in terms of compartmentation, fire stopping etc. These service runs need to be carefully detailed by way of dedicated vertical risers & horizontal runs creating sterile zones. It is Sweco’s view that although plant rooms can be shared, the service shafts should be exclusive to a section and not shared.
For example, residential service runs should not be accommodated within a non-residential riser or vice versa. It should not be possible that notifiable works within a service duct/riser could adversely affect another independent section’s services.
Where a plant room(s) is/are shared, it should be confirmed that the Principal Accountable Person has established cooperation/protocols between all the relevant Accountable Persons to manage any risk. By their nature, larger mixed-use schemes will have multiple layers of management/interoperability and will require coordinated reviews of Fire Strategy and Cause & Effect Matrixes. Simplicity in this area should be encouraged as complexity is likely to lead to management failure.
The contents of this Guidance Note are confidential to Sweco and the intended recipient and are subject to copyright in favour of Sweco. The content of this Guidance Note must not be reproduced by any person (including the intended recipient) without the prior written consent of Sweco.
The Guidance Note does not constitute professional advice and Sweco hereby offers no reliance and accepts no liability (in contract, tort (including negligence) or otherwise) for parties acting on the content of this Guidance Note without taking specific professional advice from Sweco. The Guidance Note is provided as generic guidance only and any opinion, views or advice expressed in this Guidance Note are made without any representations or provide any assurances or warranties as to the content. If you require specific advice with respect to your own project or circumstances, please contact Neil Badley.
