SWECO BUILDING STANDARDS GUIDANCE NOTE
Independent Sections Building Regulations
Introduction
This guidance note is aimed to assist Sweco Registered Building Inspectors (RBI) in verifying the clients view that the building work proposed is an Independent Section, in that it does not form part of or impact the Higher Risk section 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.
When a High Risk Building (HRB) is obtaining consent, it is considered as a whole and subject to the Gateway Process through the Building Safety Regulator (BSR). In reality the single structure could comprise of several independent sections that once complete are treated as buildings in their own right. Depending on their use, some of these independent sections may be non HRB. Consequently, future building work on them would not be controlled through the Gateway process and that section would not need to be part of the HRB registration with the BSR.
Guidance
Definition of Section
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 and can show the sections have been designed and constructed independently.
For example, two cojoined HRB’s (and registered as one HRB), each with their own stair core/entrances, separated by way of a vertical party wall into two independent sections. These were shown to be independent of each other and can therefore be classed as independent sections. Both are HRBs but would have their own independent registrations. Work to one may not affect the other. Exceptions may apply around firestopping, external cladding, balconies and shared plant etc.
Plant
Independent Sections can share plant rooms.* 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 versus. It should not be possible that notifiable works within a service duct/riser could adversely affect another independent section’s services.
Where a plantroom(s) is/are shared it should be confirmed that the multiple accountable persons have established cooperation to manage 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 Matrices. Simplicity in this area should be encouraged as complexity is likely to lead to management failure.
* For the purpose of this note, shared plant, plant rooms, and roof top plant are treated the same by way of Sweco duty holder support reviews.
Access
Where the sections are connected by a “pedestrian” connection, it should be clearly established that these connections are only for the purposes of emergency use 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.
Additional Terminology
If sections have an opening between them, the key consideration in establishing independence is whether the opening is used for emergency or maintenance purposes only and if this is case how the limited use of the opening is ensured. This is likely to include what access controls are provided and who has the responsibility to ensure their ongoing maintenance and testing.
“Exceptional Use” is a term that has started to emerge. This has no basis in law and cannot be extended beyond emergency or maintenance in establishing independence.
Also, 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.
Enclosed Walkways
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.
We are aware that consideration is being made to change this guidance when looking at hospitals and care homes. Clients can be made aware of this potential change. It cannot be used as justification until the guidance has been formally released. When/if this change is made this guidance will be updated.
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.