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The ‘ban’ of combustible materials in high rise construction

The tragic events at Grenfell Tower on the 14th June 2017 put building regulation and fire safety under a level of scrutiny that has not been seen for a generation. For years the Government has driven an agenda of deregulation seeking to minimise burden on business. Now all eyes are focused on the Government to announce the shape of the future regulatory system following the Independent Review of Building Regulations - Building a Safer Future Report or Hackitt Report as it has come to be known.

Up until now there has been relatively little in the way change. Sure, we’ve had been a number of consultations covering the use of desktop studies, clarifications to Approved Document B and the use of combustible cladding but no concrete changes announced … that was until Thursday of this week (29th November) when James Brokenshire, Secretary of State for Housing, Communities and Local Government announced amendments to the Building Regulations stating;

‘… we are determined to learn the lessons from the Grenfell Tower fire and bring about a fundamental change to ensure that residents of high-rise buildings are safe and feel safe. That is why we have set in train a programme of work to deliver that change by addressing the issues raised by Dame Judith Hackitt in her Independent review of Building Regulations and Fire Safety.’

The Minsters written statement goes on to provide detail on a ban of the use of combustible materials. Now it must be said, this is not a total ban on all combustible materials in all tall buildings that some perhaps were expecting, it does however go a good way towards removing some the previous ambiguity and tightens the rules applying to certain types of building use. The details of which are given in the changes to the Regulations themselves and the Approved Documents which give technical guidance in support of the Regulations.

The Building (Amendment) Regulations 2018

The new Regulations were laid before Parliament on the 29th November and come into effect on the 21st December 2018. They apply to England only.

The changes apply to what the regulations call a relevant building, not to be confused with a relevant building under the Fire Safety Order. The term relevant building in the case of these changes refers to a building with a storey (not including roof top plant or storeys containing plant rooms etc.) more than 18 meters above ground level and contains at least one dwelling, an institution (think hospitals) or a room for residential purposes but excluding hotels, hostels and boarding houses.

In a nutshell the changes contained within the amendment regulations are;

· A new definition of external wall

An extensive definition of what constitutes an external wall is added under the heading Interpretation (2). The definition includes;

(i) anything located within any space forming part of the wall;

(ii) any decoration or other finish applied to any external (but not internal) surface forming part of the wall;

(iii) any windows and doors in the wall; and

(iv) any part of a roof pitched at an angle of more than 70 degrees to the horizontal if that part of the roof adjoins a space within the building to which persons have access, but not access only for the purpose of carrying out repairs or maintenance;

There is also a definition for specified attachments which include balconies, solar panels and brise soleil.

· A new category under ‘material change of use’

A new category is introduced within material change of use so that works to investigate and upgrade the external walls of a building will be required where, ‘the building is a building described in regulation 7(4)(a), where previously it was not”.

7(4)(a) is a reference to relevant buildings mentioned above. So, if you convert an office building that has a storey over 18 meters into student accommodation you would need to review the external wall construction and upgrade if it I did not meet the new requirements for combustibility. If you changed the use however to a hotel the requirement would not apply. Notwithstanding this current Regulations already make allowances for considering external fire spread via the walls by virtue of Regulation 6 (c) which requires B4(1) (external fire spread – walls) to be considered when a material change of use is carried out on a building exceeding 15 meters in height.

· An additional requirement under Regulation 7, ‘materials and workmanship’

Regulation 7 (2) has been introduced which effectively states that, in relation to a relevant building, materials which become part of an external wall or specified attachment shall meet the classification for materials of limited combustibility A2 or non-combustible A1 in accordance with BS EN 13501, reference to all other classification methods (BS 476) have been removed. There are various exclusions from this requirement given in Regulation 7(3) examples being window frames, insulation and waterproofing material below ground and seals, gaskets etc.

Approved Document B - Amendments 2018

Time to get out your scissors and Sellotape as an amendment document has been published which replaces section 12 of Approved Document B, Vol 2 (AD-B) in its entirety. Regulation B4, the functional requirement remains unchanged but is supported by the new extended Regulation 7 which is replicated within AD-B for ease of reference. Regulation 7 applies in addition to Regulation B4.

The definition of external wall includes anything located within any space forming part of a wall. So, SIPs and timber frame construction do not appear permissible within a relevant building. Windows and doors are also captured within the definition of external wall however Regulation 7(3) gives us a list of items that do not need to meet the rules in 7(2) for being classified A1 or A2 which includes window frames and glass. So, spandrel panels must be A1 or A2, but the frame and glazing may be a lesser standard.

Interestingly, or confusingly, Diagram 40, which relates to the surface of external wall survives. Remember all the confusion over Class 0 rainscreen not necessarily being the same thing as limit combustibility? Well now although we still have Diagram 40, we are told that where Regulation 7(2) applies, i.e. we are working on a relevant building, this overrides diagram 40.

There remains the option to use a wall system that has been tested to BS 8414 and classified to BRE Report BR 135 Fire performance of external thermal insulation for walls of multi-storey buildings, as opposed to all materials being of limited or non-combustibility but only for buildings that do not fall into the relevant building definition.

Reference is provided to the Fire Performance of Green Walls and Roofs guidance published by DCLG. Remember if you are designing in green roofs or walls this guidance will also help you address B3 Compartmentation issues, particularly where a green roof or wall passes over a compartment wall.

Further advice

If you are planning a project and would like to discuss how we can help you with building regulations compliance, then please feel to get in touch.

References and useful links

Parliamentary statement – Grenfell Update 29th November 2018:

SI 2018 No.1230 The Building (Amendment) Regulations 2018:

2018 Amendments to Approved Document B, Volume 2:

Fire performance of green roofs and walls:

Every effort has been taken to ensure this article is both accurate and factual. We are however only human, or bear a close resemblance at least, if you do spot any inaccuracies please let us know.

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