CLADDING TECHNICAL MEMORANDUM - LABC … downloads/LABC...Where a building has a storey 18m or more...

CLADDING TECHNICAL

MEMORANDUM

Following the tragic events at Grenfell, the BRE undertook a series of 7 tests on behalf of the DCLG to assess a range of rainscreen external wall construction types. This document sets out to explain LABC Warranty’s position in respect to evidence gained from these tests in the context of the acceptable use of combustible materials in new buildings over 18.0m.

This document is not to be used for elements of a façade that are required to be fire resisting.

WHY NOW?LABC Warranty have been waiting for the government to issue an update on their advice to see whether this would provide any additional guidance to the construction industry, or any insights as to what additional guidance may be forth coming.

The government published, 25 August 2017 the results of the final one of the seven large scale BRE tests (3 storey BR 135- Annexe A, BS 8414-1 tests). The information in the test reports has now been reviewed and assimilated.

Following the completion of the last test the government issued a statement and document ‘update and consolidated advice for building owners following large scale testing’, 05 September. This statement provided some additional information but did not make any statements that required the construction industry to revise the guidance it is working to.

The update advised that the Independent Review of the Building Regulatory and Fire Safety System, designed to “Identify changes needed to make buildings safe in future” will publish an interim report at end of November 2017 and a final report will be issued in the spring of 2018.

We can expect that review will introduce changes, and recommend that further studies / reviews are carried out but until it is published we will have to wait to see what these are.

With our clients needing to know now how the current events will affect our position we have produced this document.

As the government issues additional reports and guidance LABC Warranty reserve the right to revise its position.

COMPLIANCE REQUIREMENTSTo assess whether a material or system is appropriate for use within an external cladding system, in a building whose height exceeds 18.0m the Construction Industry was, until June 2017 working to the following regulations and guidance.

Current regulation:

• The Building Regulations 2010

• Requirement Part B Fire safety, and specifically B2 – Internal fire spread (linings), B3 – Internal fire spread (structure), and B4 – External fire spread

Current Approved Document

• Approved Document B (Statutory Guidance), 7 December 2010• Approved Document B (fire safety) volume 1: dwelling houses, 2013• Approved Document B (fire safety) volume 2: buildings other than dwelling houses, 2013

Introduction

Section 12 of Approved Document B2 gives guidance on the acceptable use of combustible materials within the external cladding system. Where a building has a storey 18m or more above ground level AD B2 recommends (for the entire wall area both below and above 18m) either the use of materials of limited combustibility for all key components or to submit evidence that the complete proposed external cladding system has been assessed according to the acceptance criteria in BR135 – Fire Performance of External Thermal Insulation for Walls of Multistorey Buildings. This guidance note outlines both procedures in more detail and addresses common misconceptions relating to combustibility and surface spreads of flame ratings.

Whilst it is anticipated that changes will be made to these documents, the government has not given any indication what these changes will be. Therefore, for the time being, these remain the documents we will reference.

WHY MAKE ANY CHANGES AT ALL?Whilst the regulations and guidance documents that we work to remain unchanged the events of June 2017 have put the spotlight on many of the elements within the documents In addition the seven large scale BR 135 tests have provided a significant amount of data, whilst no means comprehensive, it does allow us to draw some conclusions and to take an informed and pragmatic approach to our warranty requirements.

The changes that we are making are designed to address the issues of interpretation, application etc and to draw on the additional information provided by the DCLG tests.

CHANGES TO LABC WARRANTY REQUIREMENTSLABC Warranty do not propose to change their requirements. LABC Warranty will continue to use the current Regulations, Approved Documents and BCA TN 18, June 2015 as the basis for assessing whether a wall construction is appropriate for use as an external cladding system, in a building whose height exceeds 18.0m.

We will however be more explicit in what we will and won’t accept as compliant / acceptable constructions in that we will stipulate:

• what we will accept as evidence of compliance• who we will accept as being competent to produce this evidence of compliance• the records that we will require as evidence of a compliant installation

CONSTRUCTIONS ACCEPTABLE TO LABC WARRANTYWhilst the regulations and guidance documents that we work to remain unchanged the events of June 2017 have put the spotlight on many of the elements within the documents In addition the seven large scale BR 135 tests have provided a significant amount of data, whilst no means comprehensive, it does allow us to draw some conclusions and to take an informed and pragmatic approach to our warranty requirements.

The changes that we are making are designed to address the issues of interpretation, application etc and to draw on the additional information provided by the DCLG tests.

OPTION 1The use of materials of limited combustibility for all elements of the cladding system both above and below 18m. This includes the insulation, internal lining board and the external facing material. Smaller gasket parts and similar low-risk items can be excluded from this requirement. The definition of MOLC is stated in Table A7 of AD B2.

LABC WARRANTY CLARIFICATIONS & ADDITIONAL REQUIREMENTS

General

We will require a cladding specification that details the wall construction for each wall type where an Option 1 approach is being applied.

Data sheets are to be provided for all materials / products within the wall construction which are being considered as Materials of Limited Combustibility (MOLC).

Insulation

LABC Warranty will require a project specific method statement (produced by the manufacturer) determining the products and methods of fixing for the wall insulation.

Cavity barriers

LABC Warranty will require a project specific method statement (produced by the manufacturer) determining the products and methods of fixing the cavity barriers.

Other elements

For the avoidance of doubt the ‘cladding system’ includes any cladding element that could influence the propagation or spread of flame of a fire, e.g. balcony surfaces such as soffits and decks, and decorative items / features such as “fins”, “columns”, etc.

OPTION 2An acceptable alternative approach (see AD B2 paragraph 12.5) is for the client to submit evidence to the Building Control Body that the complete proposed external cladding system has been assessed according to the acceptance criteria in BR135 – Fire Performance of External Thermal Insulation for Walls of Multistorey Buildings. The preferred method of demonstrating compliance is via a fire test carried out in accordance with BS8414:1 Fire performance of external cladding systems – Part 1: Test method for non-loadbearing external cladding systems applied to the face of the building or BS8414-2 Fire performance of external cladding systems – Part 2: Test method for non-loadbearing external cladding systems fixed to and supported by a structural steel frame. The test should be carried out by an independent UKAS accredited testing body. The BS8414 tests do not give a PASS / FAIL answer because the data obtained is used by different bodies with different minimum requirements. Hence, for Building Regulation purposes, any test using this method needs to be supported with a Classification Report for the proposed specification confirming that the acceptance criteria of BR135 have been met. These acceptance criteria are listed in Annex A or Annex B of BR135 and include the following:

• External fire spread – determined by a 600°C rise in temperature on the external face of the building (measured at a point approximately one storey above the fire floor) for thirty seconds or more during the initial fifteen minutes of the test.

• Internal fire spread – determined by a 600°C rise in temperature on the internal face of the building (measured at a point approximately one storey above the fire floor) for thirty seconds or more during the initial fifteen minutes of the test.

• Mechanical performance – determined by an assessment of system collapse, spalling, delamination, flaming debris or pool fires.


Information to be presented

Full copies of the BS 8414 test report(s). Noting the tests must have been carried out by a UKAS accredited test laboratory.

Information to be included in BS 8418 test certificates

Whilst Option 2 notes that BS 8414 tests do not give a PASS or FAIL, LABC Warranty will require that:

• BS 8414-1 test certificates that are submitted identify that the construction achieved the temperature and duration parameters defined for External and Internal fire spread, i.e. temperatures recorded do not exceed 600oC above Ts for a period exceeding 30 secs within the first 15 mins of the test


• These BS 8414-2 test certificates must also identify that no ‘Burn through’ event occurred

Where the original certificate does not make these clear statements (e.g. where a certificate pre-dates June 2017) LABC Warranty will require that a separate statement is obtained from the laboratory that provided the test certificate confirming the above.

Where LABC Warranty determine that the mechanical performance of the system poses a risk to the safety of persons in, or around the building, or an attending emergency service LABC Warranty reserve the right to reject the system.

Insulation


Cavity barriers


Other elements

In situations where the BS 8414 test is not a project specific test, and the project cladding system includes cladding elements which were not incorporated in the test, and that could influence the propagation or spread of flame of a fire, e.g. balcony surfaces such as soffits and decks, and decorative items / features such as “fins”, “columns”, etc these elements should either be:

• Materials of Limited Combustibility (or better), or• The subject of a Fire Specialists desktop study, and submitted together with the BS 8414 test certificate

OPTION 3If no fire test data exists for a particular system, the client may instead submit a desktop study report from a suitably qualified fire specialist stating whether, in their opinion, BR135 criteria would be met with the proposed system. The report should be supported by test data from a suitable independent UKAS accredited testing body (BRE, Chiltern Fire or Warrington Fire) and so this option may not be of benefit if the products have not already been tested in multiple situations / arrangements. The report should also specifically reference the tests which have been carried out on the product.



• The desktop study. As well as the assessment the desktop study must include:

o Full copies of all test reports and test data that are referenced in the report to substantiate a change of material must be included in Fire Specialists* report, and the tests / data must have originated from a UKAS accredited testing body

o A list that details the test reports and test data referenced in the report

o A statement confirming that author of the report has obtained the necessary permissions from the issuer(s) / owner(s) of the test certificates and test data referenced in the report to use them for this purpose

• A company / practice profile of the company submitting the assessment that evidences the company’s expertise in fire engineering, with particular reference to their expertise in of the fire engineering of facades

* The ‘Fire Specialist’ that has produced the assessment must have, as a minimum, the experience and qualifications to meet the criteria defined in Section 6 of this document.

The assessment / submission must be reviewed and signed off by a Director or Chartered Fire Engineer of the company that has carried out the assessment.

The desktop study is to be in accordance with the clarification issued by the BCA, 19 July 2017 i.e. any conclusions resulting from studies are to be supported by hard test data and based on fact and NOT purely opinion. The tests used should be those specified and carried out by UKAS accredited testing stations

A BS 8411-1 or BS 8414-2 test result must be used as the basis of the report which assesses the façade.

Note:

• Where the final construction will be installed on a non-load bearing masonry wall the ‘opinion’ of the Fire Specialist can be based on a wall construction which has previously been tested to BS 8414-1 or BS 8414-2

• Where the final construction will be installed on a non-load bearing light weight structure the ‘opinion’ of the Fire Specialist must be based on a wall construction which has previously been tested to BS 8414-2

Information to be included in the supporting BS 8414 test certificates

Whilst BCA TN 18 Option 2 notes that BS 8414 tests do not give a PASS or FAIL, LABC Warranty will require that:


• BS 8414-2 test certificates that are submitted identify that the construction achieved the temperature and duration parameters defined for External and Internal fire spread, i.e. temperatures recorded do not exceed 600oC above Ts for a period exceeding 30 secs within the first 15 mins of the test • BS 8414-2 test certificates must identify that no ‘Burn through’ event occurred

Where the original certificate does not make these clear statements (e.g. where a certificate pre-dates June 2017) LABC Warranty will require a separate statement is obtained from the laboratory that provided the test certificate confirming the above.


Insulation

LABC Warranty will require a project specific method statement (produced by the manufacturer) determining the products and methods of fixing for the wall insulation

Due to assessments that we have undertaken of the 7 DCLG tests LABC Warranty have developed a number of wall construction parameters that they consider have the potential to generate high risk build ups. The majority of these are linked to insulations when used in conjunction with wall claddings that are not MOLC. Wall constructions that are submitted which fall within these parameters are likely to receive a greater level of resistance. We would recommend submitting a proposal, or discussing these parameters with LABC Warranty prior to developing a full submission.

Rail substructures

These must be manufactured from aluminum or from a material of equal of greater resistance to fire.

Cavity barriers

Where it is proposed in the Fire Specialists report to substitute the horizontal and / or vertical cavity barrier products that were installed in the BS 8414 test with an alternative the Fire Specialist must submit test data to support this.


Other elements

The desktop study must include any cladding element that could influence the propagation or spread of flame of a fire, e.g. balcony surfaces such as soffits and decks, and decorative items / features such as “fins”, “columns”, etc.

OPTION 4If none of the above options are suitable, the client may consider addressing this issue via a holistic fire engineered approach taking into account the building geometry, ignition risk, factors restricting fire spread etc. Such an approach would be expected to follow a recognized design code such as the BS 7974 Application of fire safety engineering principles to the design of buildings suit of documents and be supported with quantitative analyses where appropriate.



Unlike the parameters the BCA have set out for this option, LABC Warranty will insist that the report is produced using the approach set out in BS 7974. Alternative approaches will only be considered if these have been agreed in advance of our quote being accepted.

• The holistic assessment. As well as the study the holistic assessment must include:

o Full copies of all test reports and test data that are referenced in the report to substantiate a change of material must be included in Fire Specialists* report, and the tests / data must have originated from a UKAS accredited testing body

o A list that details the test reports and test data referenced in the report

o A statement confirming that author of the report has obtained the necessary permissions from the issuer(s) / owner(s) of the test certificates and test data referenced in the report to use them for this purpose

• A company / practice profile of the company submitting the assessment that evidences the company’s expertise in fire engineering, with particular reference to their expertise in of the fire engineering of facades

* The ‘Fire Specialist’ that has produced the assessment must have, as a minimum, the experience and qualifications to meet the criteria defined in Section 6 of this document.

The assessment / submission must be reviewed and signed off by a Director or Chartered Fire Engineer of the company that has carried out the assessment.

The holistic assessment is to be in accordance with the clarification issued by the BCA, 19 July 2017 i.e. any conclusions resulting from studies are to be supported by hard test data and based on fact and NOT purely opinion. The tests used should be those specified and carried out by UKAS accredited testing stations.

A BS 8411-1 or BS 8414-2 test result must be used as the basis of the report which assesses the façade.

Note:

• Where the final construction will be installed on a non-load bearing masonry wall the ‘opinion’ of the Fire Specialist can be based on a wall construction which has previously been tested to BS 8414-1 or BS 8414-2

• Where the final construction will be installed on a non-load bearing light weight structure the ‘opinion’ of the Fire Specialist must be based on a wall construction which has previously been tested to BS 8414-2

Information to be included in the supporting BS 8414 test certificates

Whilst BCA TN 18 Option 2 notes that BS 8414 tests do not give a PASS or FAIL, LABC Warranty will require that:



• BS 8414-2 test certificates must identify that no ‘Burn through’ event occurred

Where the original certificate does not make these clear statements (e.g. where a certificate pre-dates June 2017) LABC Warranty will require a separate statement is obtained from the laboratory that provided the test certificate confirming the above.


Insulation


Due to assessments that we have undertaken of the 7 DCLG tests LABC Warranty have developed a number of wall construction parameters that they consider have the potential to generate high risk build ups. The majority of these are linked to insulations when used in conjunction with wall claddings that are not MOLC. Wall constructions that are submitted which fall within these parameters are likely to receive a greater level of resistance. We would recommend submitting a proposal, or discussing these parameters with LABC Warranty prior to developing a full submission.

Rail substructures

These must be manufactured from aluminum or from a material of equal of greater resistance to fire.

Cavity barriers

Where it is proposed in the Fire Specialists report to substitute the horizontal and / or vertical cavity barrier products that were installed in the BS 8414 test with an alternative the Fire Specialist must submit test data to support this. LABC WARRANTY will require a project specific method statement (produced by the manufacturer) determining the products and methods of fixing the cavity barriers.

Other elements

The desktop study must include any cladding element that could influence the propagation or spread of flame of a fire, e.g. balcony surfaces such as soffits and decks, and decorative items / features such as “fins”, “columns”, etc.

LABC WARRANTY DEFINITIONS OF APPROPRIATE PROFESSIONALS AND ORGANISATIONS TO UNDERTAKE ASSESSMENTSFire specialist

Institution of Fire Engineers – Chartered Engineer, Incorporated Engineer, Engineering Technician, Fellow, Member, graduate or Technician grade; or persons of an equivalent grade from a body specializing in Fire Engineering e.g. Society of Fire Protection Engineers (SFPE) Professional or Fellow.

Must be able to demonstrate a minimum of 3 years’ experience post education, and be able to evidence qualifications and experience that are relevant to facades, i.e. research, testing or a minimum of two years writing similar reports for facades.

Chartered Fire Engineer

Institution of Fire Engineers – Chartered Engineer.

Company / practice

A company / practice profile of the company submitting the assessment that evidences the company’s expertise in fire engineering, with particular reference to their expertise in of the fire engineering of facades.

BENCHMARKINGLABC Warranty require that a benchmark area is produced on site of a suitable scale that encompasses all the different insulation, cavity barrier and rail system elements of the wall construction(s) that are required to comply with BCA TN 18.Ideally the benchmark area would remain available for examination, i.e. unclad, until the last area of the façade that it is replicating has been completed.

OTHER CONSIDERATIONSIf the Contractor / Developer opts to use BCA TN Options 3 and 4 to obtain a warranty, they may also wish to consider whether this approach, which allows the use of products that are not non-combustible and are not of limited combustibility will be acceptable to the end user / customer.

Whilst we have no indication at this time that the government is going to change the legislation surrounding buildings over 18.0m, but our expectation is that they will. We recommend that our clients should consider that this may occur and look at ways of futureproofing their wall constructions. For example, in the government’s latest issue of “update and consolidated advice for building owners following large scale testing”, 05 September 2017, when discussing tests 5 & 6 this document states “In particular, Test 6 reaffirms that one way to ensure that a cladding system adequately resists external fire spread is for all of the relevant elements of the wall to be of limited combustibility” – this would be one method of futureproofing a wall construction.

We have not yet seen any reaction to this event from the building fire insurance industry, it is possible that buildings using insulation products that are not of Limited Combustibility (or better) will encounter higher premiums, or at the extreme end of this scenario may even struggle to find insurers that are willing to take on their policy. As further statements and information are issued by the government we will provide further guidance.

MD Insurance Services Ltd. is the scheme administrator for LABC Warranty and is authorised and regulated by the Financial Conduct Authority. Registered in England No: 3642459.

2 Shore Lines Building Shore Road Birkenhead Wirral CH41 1AU

T 0800 183 1755 E [email protected]

LABC Warranty@LABC_Warranty

CLADDING TECHNICAL MEMORANDUM - LABC … downloads/LABC...Where a building has a storey 18m or more...

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