Ron Alalouff reviews the tighter regulation of fire safety in the design and construction of buildings coming into effect on 1 December.
In the last twelve months, the government has moved to strengthen a range of fire safety provisions in building regulations and guidance, including drawing up tougher standards on the use of combustible materials on medium-rise blocks of flats between 11m and 18m high.
Changes in Act
The changes are being brought about by the Building Etc (Amendment) (England) Regulations 2022, which makes amendments to the Building Regulations 2010 and changes to Approved Document B.
Other aspects of the changes include:
- A complete ban on the use of metal composite material with an unmodified polyethylene core (the type used on Grenfell Tower) in the external walls of all new buildings and buildings undergoing building works, regardless of height or use.
- Bringing hotels, hostels, and boarding houses into the scope of the ban on the use of combustible materials in and on external walls of buildings over 18m.
- New guidance for external walls and balconies for residential buildings between 11m and 18m high.
- The continued use of structural timber in external walls in residential buildings below 18m.
ban on combustible materials
In its recent consultation on combustible materials and external building walls, the government proposed a ban on the use of combustible materials in and on the external walls of certain buildings, and in specified attachments to the external walls.
It sought views on:
- Changing the building types covered by the ban.
- Changing the height threshold of the ban.
- A ban on the use of metal composite materials with a polyethylene core.
- Attachments.
- Changing the list of exemptions.
- Changing the performance requirements of the ban.
There were 854 responses to the consultation, 376 of which were received from individuals and 299 from organizations. 179 respondents were declared as both individuals and representatives of organizations. The government considered the responses together with advice from the Building Regulations Advisory Committee and will be implementing the changes detailed below.
Buildings within scope
Hotels, hostels, and boarding houses will be brought within the scope of the current ban of 18 meters
Hotels, hostels, and boarding houses will be brought within the scope of the current ban of 18 meters, which means that the external walls of these buildings will need to meet the same performance requirements (A2-s1, d0, or better).
While the government rejected the idea of a wholesale reduction of the height threshold to 11m (with 44% of respondents to the consultation having rejected it too), it is amending Approved Document B with new guidance for buildings between 11m and 18m, setting limits on the combustibility of materials used in the walls, which would reduce the inappropriate use of combustible materials in these buildings.
Requirements at B4(1)
The government describes this as 'a proportionate response where the constraints on designers and developers increase with the height of a building'.
As part of this approach, it is reducing the height of buildings that must comply with the requirements at B4(1) of Schedule 1 when the whole building undergoes a material change of use from 15m to 11m which, it says, “will enable designers and developers to apply their professional judgment to a degree, while still setting clear expectations”.
Level of risk
The government says that the increased level of risk of such an approach is mitigated by the 2020 changes to Approved Document B, which provides for sprinklers and improved wayfinding signage for firefighters in all new blocks of flats more than 11m high.
After considerable lobbying by the timber industry, the use of structural timber in the external walls of residential buildings below 18m will be allowed to continue, if these materials are used safely by the Building Regulations.
Requirement B4
The government will clarify this guidance by setting clear limitations on some of the materials
Buildings below 18m being designed must comply with Requirement B4 of the Building Regulations. Approved Document B states that designers should give due consideration to the materials they propose to use.
The government will clarify this guidance by setting clear limitations on some of the materials used in the external wall.
Metal Composite Materials
There’s been no hesitation on the part of the government to introduce a complete ban on the use of metal composite materials with an unmodified polyethylene core in and on the external walls of all buildings regardless of height or use.
There was strong support for this in the consultation and further research has shown that this type of metal composite material poses a significant fire risk.
Attachments
Solar shading products such as blinds, shutters, awnings, and brise soleil are not required to meet the performance requirements of the ban, but must still comply with the functional requirements of Building Regulations.
The government says the clearest way to ensure safety is to apply the requirements of the ban (Class A1 or A2-s1, d0) to the curtains and slats of solar shading devices, with an exemption for ground floor solar shading devices.
This approach will ensure that smaller components enabling the operation of dynamic solar shading devices with a non-combustible curtain are not required to meet the performance requirements of the ban, allowing the use of more efficient products while not compromising safety.
Exemptions
The consultation proposed a temporary relaxation of the ban relating to cavity trays under S.11
Cavity trays are installed in wall cavities to capture moisture that penetrates the outer face of the wall, preventing dampness. The consultation proposed a temporary relaxation of the ban relating to cavity trays under S.11 of the Building Act 1984.
However the government does not believe it is appropriate to permanently exempt cavity trays, as this would hinder innovation in the development of additional compliant products, and it wants to see non-combustible cavity trays being used in external walls where they are readily available after the temporary exemption expires.
Materials
Limited exemptions will also apply to the following materials:
- Fiber optic cables: The ban currently exempts electrical installations within the external wall construction such as wiring cables and sockets, but this does not extend to fiber optics cable, as these wires do not carry current. The government will therefore exempt fibre optic cables alongside electrical installations.
- Roofing components: To inhibit the ingress of water, the design of the junction between an external wall and a roof often requires that roof membranes extend into the external wall, and these are exempted from the requirements of the ban. The government will provide clarification on the application of the ban on roofing membranes in guidance to the building regulations.
- Laminated glass: Glass – including laminated glass – is currently exempt from the ban only when included within a window frame. Laminated glass is often used in the construction of balconies, but there is no laminated glass for external use available to achieve the appropriate classification (i.e. class A1 or A2-s1, d0). The government has commissioned research into the use of laminated glass in balconies to make an informed decision about whether laminated glass should be exempted or not, but in the meantime continues to require it to achieve classification when used in a balcony.
- Materials below ground level: Waterproofing and insulation materials used in external walls below ground level are exempt from the requirements of the ban as they need to be water and moisture-resistant, and non-combustible materials are not typically so. However, there is sometimes a need to continue these materials above ground to prevent moisture from penetrating the external walls. Waterproofing and insulation materials up to 300mm from ground level will therefore be exempted from the ban.
- Structural elements and engineering timber: The use of combustible materials, including timber, in and on the external walls of new high-rise blocks of flats more than 18m in height including hospitals, care premises, and student accommodation, is banned. Although the government recognizes the potential environmental benefits of timber construction where it can be used safely, it is not yet satisfied that the case is strong enough to justify an exemption for structural timber in the highest-risk buildings. It has, meanwhile, commissioned research to look at the issue, and how the use of modern methods of construction will inform the development of building regulations and any other necessary action.
Performance requirements
The A2 and A1 classifications apply to materials tested vertically as a wall, and there are alternative classifications (Class A2fl-s1 and A1fl) that are available for materials tested horizontally as a floor.
Several products used for balcony floors are currently only tested to the A2fl-s1 or A1fl classification and as such, do not meet the requirements of the ban.
Additional classifications
A large majority of respondents agreed with the proposal to exempt materials achieving the classifications
In the consultation, a large majority of respondents agreed with the proposal to exempt materials achieving the classifications required for materials used horizontally to include Class A2fl-s1 and Class A1 fl.
The government will therefore allow the use of these additional classifications for materials tested horizontally by exempting them from the regulations. Finally, the reference to BS EN 13501-1 will be updated to the latest version of the standard.
Implementation
All the amendments will be implemented through changes to the building regulations and Approved Document B. Changes to building regulations will come into force on 1 December 2022 and will apply unless an initial notice, building notice, or full plans have been deposited before then, and work has either started or starts within six months of that date.
The changes to Approved Document B will take effect on the same day and the same transitional arrangements will apply. The relaxation of the requirement of cavity trays was due to take effect on 1 June 2022.
Fire safety guidance
Other changes to fire safety guidance include all new residential buildings over 11m having to have a Secure Information Box to give fire and rescue services access to key details of the buildings, and new residential developments over 18m also having to incorporate an Evacuation Alert System to help fire and rescue services inform residents of a change in evacuation strategy during an incident.
At the announcement of the changes in June, Gavin Tomlinson, Chair of the National Fire Chiefs Council Protection and Business Safety Committee, said, “NFCC especially welcomes the introduction of emergency evacuation alert systems in new buildings over 18m."
Secure Information Boxes
Gavin Tomlinson adds, "We also support the inclusion of Secure Information Boxes in buildings over 11m, which will give fire and rescue services access to important details about a building and its residents in the event of a fire."
He continues, "On the changes to building regulations, we are encouraged that unsafe MCM PE cladding panels are banned on all buildings and that the government has promised stronger safety standards for the use of combustible materials on external walls."
