AN OVERVIEW OF THE MAIN AMENDMENTS TO APPROVED DOCUMENT B

When the UK government published Regulation 7, it pledged to regularly review and update it. And indeed, June 2022, amendments to the Building Regulations 2010 were introduced, as well as to the accompanying Approved Document B (ADB) on fire safety, Volumes 1 and 2. The majority of amendments to ADB apply from December 1st 2022 (with a transitional period of 6 months), and we list the most important ones in what follows. More specifically, we will zoom in on the changes that pertain to the ban on combustible materials and to the external walls of buildings, as well as touching briefly on some general changes to Approved Document B. 1. COMBUSTIBLE MATERIALS Several sections in ADB that pertain to the ban on combustible materials in Regulations 7(2) to 7(4) have been updated, such as Section 10 of ADB Volume 1 and Section 12 of Volume 2. Four main changes can be distilled from those updates. 1.1. INCLUSION OF HOTELS First of all, the definition has been expanded of what constitutes a “relevant building” (a building that the ban on combustible materials applies to). Before the recent amendments to ADB, relevant buildings contained one or more dwellings or an institution, such as student accommodation, care homes, sheltered housing or hospitals, with a storey 18 of metres or more. (Note that here, top storey height is used as a threshold for application. The height to the top storey is measured from the lowest external ground level adjacent to the building up to the top floor surface of the top storey.) New as of December 1st 2022 is that hotels, hostels and boarding houses are now also included in the scope, which means that their external walls or specified attachments should be made from materials with European classification A1 or A2-s1, d0. 1.2. SOLAR SHADING Secondly, solar shading has been reinserted in the ban. In the original ban, it was included as a specified attachment. A subsequent high-court judgment removed solar shading, but the government has now reincluded it – along with two conditions. When they are attached to the external wall of a relevant building, the curtains and slats themselves have to be made from non-combustible materials that achieve A1 or A2-s1, d0, but the other components do not have to meet this requirement. Solar shading devices installed up to 4.5 metres above ground level do not have to meet the requirement either. 1.3. CHANGES TO EXEMPTIONS Regulation 7(3) exempted some situations, materials and products from the A1 or A2-s1, d0 requirement of Regulation 7(2). For instance, door and door frames were excluded, as well as insulation and waterproofing used below ground. The amended version of Approved Document B contains three further or altered exemptions, namely: Insulation and waterproofing materials used up to 300 mm above ground level are now also exempt (so not just those used below ground). Fibre optic cables are now also on the list of materials exempt from the combustible materials ban. A1fl or A2fl-s1 materials are allowed on balcony floors with an imperforate substrate under the whole layer. In other words: the top layer of a balcony floor can meet the required standard using the horizontal-testing equivalent of the existing standard (which requires materials to be tested vertically). 1.4. UPDATE OF THE CLASSIFICATION STANDARD The classification standard that applied when the original ban on combustible materials came into effect (namely BS EN 13501-1:2007 + A1:2009) has been updated. Now, BS EN 13501-1 2018 is the standard when classifying materials as A1 or A2-s1, d0. 2. EXTERNAL WALLS OF BUILDINGS Furthermore, there have been two updates in relation to the external walls of buildings. 2.1. AN UPDATE TO SECTION 10 OF ADB VOLUME 1 FOR EXTERNAL WALLS Government considered changing the 18-metre height limit, further extending the ban on combustible materials to buildings of 11 metres high. Eventually, the threshold of the ban was not reduced, but new guidance for buildings between 18 and 11 metres in height has been introduced. External surface of the wall Table 10.1 in ADB Volume 1 (‘Reaction to fire performance of external surface of walls’) now has a new line for all residential purpose groups – or rather, two lines, because this group is subdivided into buildings of more than 11 metres in height and buildings of 11 metres or less. Building height is measured from the mean ground level to the mean roof level, or the top of the parapet (whichever is highest). For buildings of more than 11 metres in height, the external surfaces of external walls must be A2-s1, d0 materials or better. For buildings of 11 metres or less, regulations depend on whether the external walls are less than 1000 mm away from a relevant boundary or not – the term ‘relevant boundary’ referring to “the boundary or notional boundary (a boundary presumed to exist between two buildings on the same site) that one side of the building faces and/or coincides with, and that is parallel or at an angle of a maximum of 80 degrees to that side of the building.” The outermost external material of an external wall less than 1000 mm away from a such a boundary has to achieve Class B-s3, d2 or better. There are no provisions for walls 1000 mm or more away from a relevant boundary. In other words, PAVATEX (which achieves Class E) is a perfect solution in such cases. Insulation and filler materials A new paragraph 10.7 has been added, too. It states: “In buildings that include a ‘residential’ purpose (purpose groups 1 and 2) with a storey 11m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s1, d0 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 8.2 in Section 8. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.” So, for residential buildings with a storey 11 metres or more above ground level, insulation products and filler materials used in the external wall need to be A1 or A2-s1, d0, except between two leaves of masonry that comply with the provisions in Diagram 8.2. Balconies Lastly, there is a new paragraph 10.10 that applies to materials used for the balconies in residential buildings with a storey of 11 metres or more above ground level. The amended ADB introduces the exemption of A1fl and A2fl-s1 rated balcony decking from the requirement of an A2-s1, d0 fire rating if the entire layer has an imperforate substrate layer under it. 2.2. BAN ON METAL COMPOSITE MATERIALS IN EXTERNAL WALLS Metal composite materials are now completely banned from being used in the external walls or specified attachment of any building regardless of its height or purpose. It does not matter whether it is a new build or a building undergoing refurbishment. 3. GENERAL CHANGES TO APPROVED DOCUMENT B Finally, some general changes to ADB Volume 1 are worth mentioning briefly. Regulation 6(1)(c), which lists the requirements when a material change of use is undertaken, has been amended. Requirement B4(1) used to be applicable for buildings exceeding 15 metres, but this threshold is now reduced to 11 metres. From June 1st 2022 onwards and lasting for 18 months, the requirement for cavity trays being A1 or A2-s1, d0 is temporarily dispensed with, due to a shortage in suitable (non-combustible) cavity trays.

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