Part B changes being phased in to improve fire safety

In September 2024, the Ministry of Housing, Communities and Local Government (MHCLG) announced updates to volumes 1 and 2 of Fire Safety: Approved Document B for England, with the first of these taking effect on 2 March 2025.

One focus of these updates is replacing and expanding sections of Building Regulation 38 to take account of more detailed obligations on the responsible person and relevant dutyholders, with regard to the fire safety information that is provided at completion.

These amendments are comparatively minor, taking the opportunity to update the approved document's guidance and definitions to align with the Building Safety Act 2022.

The UK government has also decided to extend the requirement for sprinklers to all new care homes irrespective of height; such facilities will be expected to limit compartment sizes to ten beds and ensure doors are self-closing as well.

In recognising the needs of the few parts of the industry that still use BS 476, such as manufacturers, the government is implementing changes to the guidance in two stages: first removing references to BS 476 associated with reaction to fire and roof covering classifications, then at a later stage removing all references to the series associated with fire resistance.

The amendments to Part B in England that came into effect in March therefore removed mentions of BS 476-22, leaving BS EN 13501 as the sole standard with which roofs should comply. This aims to enhance fire protection by simplifying the specification routes in Approved Document B, using the more robust, internationally recognised approach that is regularly reviewed.

A booklet accompanies Circular 01/25 and gives details of the amendments that came into force in March, subject to the transitional provisions detailed below.

Among these amendments is a recommendation for second staircases in residential buildings more than 18m tall, originally published in the booklet accompanying Circular 01/2024.

Finally, a third booklet accompanies Circular 05/2024 to detail amendments coming into force in September 2029, again subject to transitional provisions. This highlights the removal of all the remaining references to BS 476 in relation to fire resistance.

As a result of all these changes, the regulations now refer to the 2019 edition of Approved Document B incorporating 2020, 2022 and 2025 amendments, as well as those to come in 2026 and 2029, for use in England. The Approved documents have been coloured coded to help define the changes. The 2026 amendments are in purple, and the 2029 amendments are in orange.

A full transition to the European standard will enable government to use updated standards as compared with the current national ones which cannot be updated, thereby future proofing the building stock.

The transition period is designed to give the construction products industry time to develop standards that support the transition away from the national classes and comply with the European equivalents.

The arrangements aim to ensure that products already tested to BS 476 can continue to be used during the transition period, and that the necessary retesting to BS EN 13501 can take place.

Although the 2025 amendments took effect in March, the 2019 edition of Approved Document B incorporating the 2020 and 2022 amendments will continue to apply where a building notice or an initial notice has been given to the relevant authority, or it has been sent a building control approval application with full plans before that date.

'Building notice', 'initial notice' and 'building control approval application with full plans' are all defined in the Building Regulations 2010.

The relevant building work also needs either to have started and been sufficiently progressed by 2 March 2025, or begun and have been sufficiently progressed within six months of that date; that is, by 2 September 2025.

So far as the transitional arrangements are concerned, work is to be regarded as 'sufficiently progressed': 

• where it consists of the construction of a building and the pouring of concrete for the permanent placement of the trench, pad or raft foundations has started, or the permanent placement of piling has started
• where it consists of work to an existing building and has started
• where it consists of a material change of use of a building, and work to effect that change has started.

As with this year's amendments, the 2019 edition of Approved Document B incorporating these and the 2020 and 2022 changes will continue to apply where a building notice, initial notice or building control approval application with full plans has been made before that date.

Similarly, the work must already have started by then and be sufficiently progressed or begin and progress sufficiently within not six but 18 months.

The changes include a new recommendation for more than one common staircase to be provided in blocks of flats with a storey 18m or more in height, and design provisions to support the use of evacuation lifts in blocks of flats.

The final amendments will take effect on 2 September 2029 in England, until which time the 2019 edition incorporating subsequent amendments will continue to apply. This will be under similar circumstances as the 2025 amendments; that is, a building notice, initial notice or application with full plans has been made before that date, and the work has started and is sufficiently progressed by then or within six months.

These changes will come into force on 20 December this year, affecting regulations 2(6), 6 and 7 as follows. 

• There is a ban on using 'relevant metal composite material' in part of an external wall or specified attachment as part of the building when undertaking work. The ban will apply to both new buildings and buildings being refurbished, regardless of their height or use where building work takes place. This is considered to be applicable to the erection or extension of a building as well as where material alterations and/or material changes of use take place or work required by regulations 22, 23 and 28 which relate to changes in energy status and upgrading/renovation of thermal elements and related consequential improvements to energy performance.
• Regulation 2(6)(b) newly defines such material as any panel or sheet no more than 10mm thick comprising a number of layers. Two or more of these layers will be made of metal, alloy, or metal compound, and one or more must be a substantial layer of a material with a gross calorific value of more than 35MJ/kg when tested in accordance with BS EN ISO 1716: 2018. A substantial layer is defined as being at least 1mm thick or with a mass per unit area of at least 1kg/m².
• Regulation 2(6) also now defines solar shading devices and refers to them in the definition of 'specified attachment', although this excludes such devices installed less than 4.5m high. Components of devices whose primary function is to provide shade – such as awning curtains or slats – are to be exempted but thereby have to meet the reaction to fire classification standard in Building Regulation 7 where used on a relevant building.
• The definition of ‘relevant building’ is in turn extended to ban the use of combustible materials in external walls in regulations 6(3) and 7(2) on hostels, hotels, and boarding houses.
• The list of exemptions from the requirement that materials meet the classification for reaction to fire in regulation 7 now additionally includes fibre-optic cables, insulation and waterproofing materials used from ground level up to 300mm. Any materials that form the top horizontal floor layer of a balcony may also meet the equivalent horizontally tested classification, so long as there is an imperforate substrate beneath.
• Regulation 6(1)(c) is amended so that, where there is a material change of use to a whole building exceeding 11m in height, any necessary work must ensure the external walls comply with Part B4(1) of Schedule 1 of the regulations; this was previously only required for buildings more than 15m. Where a material change of use relates to just part of such a building, as outlined in regulation 6(2)(c), any necessary work must still ensure the external walls of the whole building meet the same requirements.

The document included the changes described above, as well as:

• setting limits on the use of certain combustible products for residential buildings with a storey between 11m and 18m
• mandating evacuation alert systems in accordance with BS 8629 in blocks of flats with a top storey more than 18m above ground level
• requirements to install secure information boxes in all new blocks of flats with a floor of 11m or more above ground level
• requirements for floor identification and flat wayfinding signage.

Although consultation on Approved Document B in Wales ran from October 2023 to January 2024 – and the government response to it suggested moving reference to the national BS 476 fire testing classifications from the main document into the appendix – the amendment slip does not mention implementing this proposal. However, it is understood that this is likely to happen after the next revision to the document in Wales.

The 2013 edition of Approved Document 7: Materials and Workmanship with 2020 amendments will be withdrawn in Wales on 20 December 2025, when a version also including the 2025 amendments will take effect in the principality. The most recent amendments concern the changes made to regulation 7 by the new regulation 2(4).

The main changes to Regulation 7(2) set requirements in respect of external walls and specified attachments as follows. 

• Regulation 7(2) applies to any building with a storey at least 18m above ground level and which contains one or more dwellings; an institution; or a room for residential purposes, excluding any room in a hostel providing temporary accommodation to those who are ordinarily resident elsewhere, hotel or a boarding house. This includes student accommodation, care homes, sheltered housing, hospitals, and dormitories in boarding schools.
• Regulation 7(2) requires that all materials which become part of an external wall or specified attachment achieve European Class A2-s1, d0 or Class A1 when classified in accordance with BS EN 13501- 1:2018. Materials achieving limited combustibility cannot be deemed to meet the requirement using an alternative classification method.
• Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments. While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.

Any material achieving class A1fl or A2fl-s1 in accordance with BS EN 13501-1 is exempted when it meets both of the following conditions:

• it forms the top horizontal floor layer of a balcony
• it is provided with an imperforate substrate under it which extends to the full size of the class A1fl or A2fl-s1 material.

The amendments to Regulation 7 apply from 20 December 2025 to any building with a storey at least 18m above ground level that contains one or more dwellings, including student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools.

None of these requirements apply to work where a building notice, initial notice or full plans have been given to a local authority before the amended regulations come into force in Wales on 20 December, provided that the work has already started or begins within six months; that is, by 20 June 2026.

The Welsh government's announcement closely aligns with the June 2022 changes to the Building Regulations 2010 already in force across England.