The new Approved Documents, introduced as the ‘clarified Approved Documents’, will come into force on 30th August this year.
As well as generally improving the accessibility and layout, a focus has been put on clarifying the language used in the documents and examples have been included to further reduce ambiguity. This article sets out the changes and clarifications made, particularly in Approved Document B: Volume 2, specifically Section 12.
The changes will only apply to buildings and building work in England. Given the improvement to the Approved Documents, it is likely that this application will be extended beyond, but as of 30 August 2019, only England will enjoy the upgrade.
The new documents do not apply in any case where a building notice or an initial notice has been given to, or full plans deposited with, a local authority and either the building work to which it relates:
- has started before the date that a building notice, initial notice or full plans have been deposited, or
- is started within the period of two months beginning on that date the building notice, initial notice or full plans have been deposited.
Section 12
This latest upgrade, announced on 5 July 2019, was largely in response to the Grenfell Tower fire and subsequent Hackitt Review. As a result, aside from design of blocks of flats being moved from Volume 2 to Volume 1, Section 12 has undergone the most noticeable change. Accordingly, this will be the focus of this article.
The first and most obvious change is the drastic shortening of the introduction to a much more concise and digestible short paragraph, outlining the purpose of the section. It then does away with the reference to Table A1 in Appendix A, instead dividing up the requirements into their relevant sections (General provisions, Loadbearing elements or structures, and Resisting fire spread from one building to another). The previously used table is convoluted and often refers readers, already referred to this table, off to another table, and so this change certainly lives up to the ‘clarified’ tag.
‘Combustibility of external walls’ has unsurprisingly undergone changes. The first introduces the primacy of Regulation 7(4) of the Building Regulations, the second states that consideration should be given to the combustibility of materials used for the external walls of any buildings of any height. Though the latter should have been dictated by common sense, a provision clearly stating it is still welcome. The reference to full-scale BRE testing remains.
The most crucial changes come in the next provisions, covering the materials and products that can be used on external surfaces. Diagram 40 under the previous iteration has been replaced by the far clearer Table 12.1. While providing far greater clarity than Diagram 40, the table also introduces the necessity for materials to be Class A2-s1, d0 or better for ‘Relevant Buildings’ (regulation 7(4)) rather than just of ‘limited combustibility’ as per the old requirements. This is reinforced in the following provisions that also highlight where regulation 7(2) applies, then it prevails over the provisions in this section.
Section 9 remains the provision that deals with cavities and cavity barriers, and so subsection 12.8 is unchanged. Finally, 12.9 once again notes the introduction of Table 12.1, the primacy of regulation 7(2), and the change from ‘limited combustibility’ to Class A2-s1, d0 or better.
Given the references to the Building Regulations in the new version, the update includes further provisions to clarify their impact on Approved Document B. These subsections cover the materials, material change of use, and additional considerations for the regulations, and how they apply to the new documents. The inclusion of these subsections ensures that any previous references to the Building Regulations throughout Section 12 are easy to understand and maintain the underlying theme of clarity.
The table below outlines the updates to Section 12 from the previous version of Approved Document B to the 2019 version.
2019 | Previous | |
Introduction | 12.1 simple introduction | 12.1 and 12.2 |
Fire Resistance | 12.2 Fire resistance for external wall requirements have been moved to Section 5 (General provisions), Section 7 (Loadbearing elements or structures) or Section 13 (Resisting fire spread from one building to another). | 12.3 Fire resistance previously given in Appendix A, Table A1. |
Combustibility of External Walls
| 12.3 Unless external walls fall under Regulation 7(4) of the Building Regulations, must achieve either: a. provisions 12.5 – 12.9, or 12.4 Buildings of any height or use should have their choice of materials considered for external walls to reduce fire risk. | 12.5 Almost identical to the requirements under a. and b. but no reference to Regulation 7(4) of the Building Regulations. |
External Surfaces | 12.5 External walls should comply with the provisions in Table 12.1: ‘Relevant Buildings’ (regulation 7(4)) must have Class A2-s1, d0 or better.The table also shows the requirements for a building for “assembly and recreation” as well as “any other building”. | 12.6 Reference to Diagram 40 (provisions for external surfaces or walls). |
Materials and Products | 12.6 In a building with a storey 18m or more in height 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-s3, d2 or better. This restriction does not apply to masonry cavity wall construction which complies with Diagram 9.2 in Section 9. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph. 12.7 Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government. | 12.7 In a building with a storey 18m or more above ground level any insulation product, filler material (not including gaskets, sealants and similar) etc. used in the external wall construction should be of limited combustibility. This restriction does not apply to masonry cavity wall construction which complies with Diagram 34 in Section 9. |
Cavities and Cavity Barriers
| 12.8 Cavity barriers should be provided in accordance with Section 9. 12.9 If not subject to Table 9.1 (external cladding system with a masonry or concrete inner leaf), cavities should also meet the provisions of Table 12.1 and provisions in Section 9, but where regulation 7(2) applies, that regulation prevails over the guidance provided in Table 12.1 and Section 9. | 12.8 Cavity barriers should be provided in accordance with Section 9. 12.9 In the case of an external wall construction, of a building which, by virtue of paragraph 9.10d (external cladding system with a masonry or concrete inner leaf), is not subject to the provisions of Table 13 ‘Maximum dimensions of cavities in non-domestic buildings’, the surfaces which face into cavities should also meet the provisions of Diagram 40. |
