Building standards - (fire safety) external wall systems: consultation analysis

2. Part 1 – Mandatory Standard 2.7

2.1 Introduction

2.1.1 Following two meetings of the building standards (fire safety) review panel, it was suggested that changes are made to the wording of Mandatory Standard 2.7 (spread on external walls). The standard is shown in the quote below with the text to be deleted marked with a strikethrough and the proposed additional text shown in bold.

" Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building is inhibited, does not unduly promote fire spread taking into account the height and use of the building."

2.2 The purpose of the proposed change to the standard was to provide clarity of intent taking into account current guidance.

2.2 Question 1 – Change to Mandatory Standard 2.7

2.2.1 Question 1 asked respondents whether they agreed or disagreed with the proposal to remove the words "is inhibited" in the mandatory standard which is considered ambiguous and replace with the words in bold (in the quote above) to provide clarity of intent in the supporting guidance.

2.2.2 Table 2 below shows whether respondents agreed with the proposal to remove the words "is inhibited" and replace them with "does not unduly promote fire spread taking into account the height and use of the building" in the mandatory standard. The majority (55%) of responses were supportive of the proposal (agreeing or strongly agreeing) with 28% of respondents disagreeing or strongly disagreeing with the proposal. A further 16% of respondents were neutral on the proposal.

2.2.3 Taking agreement and strong agreement together, there was majority support for this proposal across all categories except for individuals and research establishments/fire test houses. Individuals were quite broadly split across agreement, disagreement and neutral. Research establishments/fire test houses disagreed with the proposal.

Table 2: Summary of responses to Q1 on the removal of the words "is inhibited" and their replacement with "does not unduly promote fire spread taking into account the height and use of the building"?

	Strongly Agree	Agree	Neither Agree or Disagree	Dis-Agree	Strongly Dis-Agree	Not Answered	Total
Construction Ind.	2	2	2	-	-	-	6
Consultancy	2	2	1	-	2	-	7
Individuals	4	5	4	3	6	-	22
Local Authorities	4	1	-	2	1	-	8
Manufacturers	1	4	-	1	-	1	7
Other	3	2	3	1	-	-	9
Research Estab./Fire Test House	-	-	-	2	-	-	2
Trade Association	3	5	2	3	-	2	15
Total	19	21	12	12	9	3	76
% respondents answering question	26	29	16	16	12		100

Note: Percentages may not sum due to rounding

2.2.4 There were 57 comments made in response to this question. Responses are considered separately for those agreeing and those disagreeing with the quantitative part of the question.

Agreeing with the Proposed Wording

Improves Clarity

2.2.5 Many respondents from all categories except individuals and research establishments/fire test houses supported the proposed wording as they felt it provided greater clarity on the intention of the mandatory standard. The proposed wording was felt to address two key aspects which determine the fire safety of a building – height and use of the building. While there was general support for the reference to height and use, one respondent felt that reference to height and use should be removed as height and use of buildings are addressed elsewhere in the Technical Handbooks.

2.2.6 Several respondents also highlighted that the proposed wording aligns more closely with the functional requirements given in the Building Regulations for England and Wales.

Suggested Alternative Wording

2.2.7 Although agreeing with the proposed wording of the mandatory standard, some respondents made comments on the wording including:

• The wording chosen becomes confused by the repeated use of "fire" and "spread".
• "does not unduly promote" is weak as the word "unduly" is open to interpretation or at least is as ambiguous as "inhibited". One respondent suggested deleting "unduly".
• In contrast another respondent felt that "unduly" was appropriate as products used as cladding should not encourage vertical fire spread to a degree that would unduly impact on the safety of life.

2.2.8 A few respondents suggested alternative wording which is shown in bold in the quotes below:

"Every building must be designed and constructed in such a way that, in the event of an outbreak of fire within the building or from an external source, the spread of fire on the external walls of the building is not unduly promoted, taking into account the height and use of the building"

"Every building must be designed and constructed in such a way that, in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building, taking account of its height and use, is not unduly promoted"

"Every building must be designed and constructed in such a way that, in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building should not unduly promote fire spread taking into account the height and use of the building"

"Every building must be designed and constructed in such a way that, in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building does not unduly promote fire spread taking into account the height and use of the building"

General Points Supporting the Proposal

2.2.9 A couple of more general comments were made including:

• The need to "flag" a building with external combustibility for insurance and occupier safety reasons.
• The need to consider the wall build up. If the wall is a brick and block cavity insulation wall, there is negligible risk from having combustible insulation within the cavity. If the wall is externally insulated with a rain screen cladding system, the risk is higher depending on the height and use of the building.

Disagreeing with Proposed Wording

No Less Ambiguous

2.2.10 While respondents disagreeing with the proposed change were often supportive of the intent of the change, many respondents across all categories, excluding the construction industry, felt that the proposed wording was just as vague or open to interpretation as the original wording. Indeed, the original word "inhibited" was felt to be stronger by a few respondents. As one respondent stated:

"the new wording is of a lower standard than the existing regulation as the wording implies that the materials in the external wall may allow some degree of fire spread across the external wall construction whereas the existing wording implies that the external wall should act to limit spread of fire".

2.2.11 The use of the words "unduly promote" were felt to be ambiguous. Several respondents suggested removing "unduly" from the proposed wording such that the sentence reads "…does not unduly promote fire spread…". This point was also made by a respondents supporting the proposed wording (paragraph 2.2.7, second bullet point above).

2.2.12 Other alternative wording is shown in bold in the quotes below:

"Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, or from an external source, the external walls do not unduly promote fire spread taking into account the height and use of the building"

"Every building must be designed and constructed in such a way that, in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building do not unduly promote fire spread taking into account the height and use of the building"

"Every building must be designed and constructed in such a way that, in the event of an outbreak of fire within the building, or from an external source, the spread of fire on the external walls of the building is slowed by the geometric arrangement of non-combustible and fire resisting construction in the external wall to provide sufficient time to ensure the Life Safety of occupants"

2.2.13 The last suggested wording in paragraph 2.2.12 reflects a view that life safety would be better served if buildings were protected as an asset or as property.^[2] This would require the mandatory standard to allow sufficient time for evacuation (self-evacuation through to rescue) by slowing fire spread to the adjacent fire resisting compartments on the external wall.

2.2.14 One respondent also provided some examples of wording of the performance requirements for external walls from other countries including:

• England-Building Regulations 2010 (as amended 2018):
  "B4. (1) The external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and position of the building"

• Republic of Ireland- Building Regulations (Amendment) Regulations 2006:
  "The external walls and roof of a building shall be so designed and constructed that they afford adequate resistance to the spread of fire to and from neighbouring buildings."

• Republic of Ireland- Technical Guidance Document B Reprinted edition 2020:
  "4.1.5 The external envelope of a building should not provide a medium for fire spread"

• Australia- Performance Requirement CP2 of NCC Volume One:
  "a) A building must have elements which will, to the degree necessary, avoid the spread of fire—
  ...
  (iii) between buildings; and
  (iv) in a building."

• New Zealand- New Zealand Building Code -
  "C3—fire affecting areas beyond the fire source
  Provisions
  Functional requirement
  ...
  c3.3 Buildings must be designed and constructed so that there is a low probability of fire spread to other property vertically or horizontally across a relevant boundary."

• Canada- Division A Compliance, Objectives and Functional Statements Part 3 — Functional Statements
  "3.2.1. Functional Statements
  3.2.1.1. Functional Statements
  1) The objectives of this (Bylaw) are achieved by measures, such as those described in the acceptable solutions in Division B, that are intended to allow the building or its elements to perform the following functions (see Appendix A):
  ....
  F03 To retard the effects of fire on areas beyond its point of origin."

2.2.15 The examples show that the wording of the requirements of other countries all relate to the materials actively limiting the spread of fire rather than the material not unduly promoting the spread of fire.

2.2.16 Given the perceived ambiguity of "unduly promote", it was stated that the guidance in the Technical Handbook would have to provide the required clarity. However, it was suggested by one respondent that the guidance to which the new wording would apply is buildings over 11m in height, while the functional standard applies to buildings of any height. The standard would imply that all buildings should be constructed in a manner that does not promote fire spread, but buildings under 11m are permitted to have European Classification E which does not have a restrictive role in the spread of fire.

Neither Agreeing or Disagreeing with Proposed Wording

2.2.17 Several respondents who did not agree or disagree with the proposal felt the proposed wording was still ambiguous and that the proposed wording would not have a significant effect on the understanding of the mandatory standard. It was also suggested that further clarification could be provided in guidance if necessary, rather than through changes in legislation.