Introduction

The ABI in their document ‘Technical Briefing; Fire Performance of Sandwich Panel Systems’ and Factory Mutual (FM) strongly recommend the use of certificated panels for new build projects. UK manufacturers have responded to this approach and all EPIC members now offer PIR insulated panel systems that satisfy the test and certification criteria of The Loss Prevention Certification Board (LPCB) and/or FM Global.

Certification of panel systems by both organisations is based on their performance in large-scale room tests incorporating a significant fire source. The tests indicate the likely performance in the developing stage of a fire and have a good correlation with actual practice in known fire scenarios. Additional approval standards are available that incorporate tests illustrating a level of fire resistance.

The Loss Prevention Certification Board (LPCB) and FM Global approved PIR cored panels are generally acceptable to insurers.

Nevertheless ABI also recognise that there is a role for non-certificated panels used as the external envelope in low/medium risk applications. This recognition is particularly relevant to the use of PUR insulated panels on existing buildings.

The Loss Prevention Certification Board (LPCB) tests

LPCB tests assess various levels of fire performance including reaction to fire; reaction and resistance to fire; and a separate grade for resistance to fire only.

Panels for external use are tested in accordance with LPS 1181: Part 1 “Requirements and Tests for built-up cladding and sandwich panel systems used as the external envelope of buildings”.

Under LPS 1181: Part 1, approvals are given to two standards, A and B.

  • Grade Ext-A panels for wall systems only and need to attain minimum 30 minutes fire integrity and 15 minutes insulation according to fire resistance test BS 476 part 22
  • Grade Ext-B approvals for roofs and walls not requiring fire resistance are to determine that the panel doesn’t propagate or aid spread of fire by construction

Both types of approved panels are typically of the same design. The difference in performance is in the properties of the PIR core used and the type of joint detail and method of fixing. Different panel manufacturers’ standards vary considerably even within the approved ranges. Panel cores are difficult to access though some are currently subject to identification marks. All PIR cores are the same colour and it is important that all literature provided with panels purchased and installed is retained.

Panels for internal use are tested in accordance with LPS 1181: Part 2 ‘Requirements and tests for wall and ceiling lining systems for use as internal construction in buildings’ or LPS 1208 “Fire test requirements for elements of construction used to provide compartmentation”.

Under LPS 1181: Part 2, approvals are given to three standards:

  • Int-3: Panels satisfying the LPS 1181 test as for external panels but tested to the as-built internal configuration
  • Int-2: As Int-3 and satisfying 30 minutes fire integrity and 30 minutes insulation according to fire resistance test BS 476 part 22
  • Int-1: As Int-3 and satisfying 60 minutes fire integrity and 60 minutes insulation according to fire resistance test BS 476 part 22

The alternative LPS 1208 again offers approvals to two standards, ‘Normal’ and ‘High Risk’. ‘Normal’ relates to attaining 30 minutes integrity and 30 minutes insulation. ‘High Risk’ equates to 60 minutes integrity and 60 minutes insulation.

LPCB Approved Panels

The ABI technical Briefing ‘Fire performance of sandwich panel systems (May 2003, rev Sept 2008)’ is an independent and authoritative document that gives information and guidance on insulated panel systems.

The document supports the use of approved panel systems and in particular the LPCB approved panels:

“Where high levels of risk management are not achievable due to the nature of the processes in the building and/or the quality of the management demonstrated, and the risk of ignition is high, the use of panel systems with high fire performance characteristics should be considered. Systems meeting accreditation schemes such as LPCB 1181 demonstrate such characteristics.”

– ABI Technical briefing: Executive summary.

The Technical Briefing also makes a number of other important points relating to LPCB approved panels:

“For insurance underwriting purposes, Insurers use the Design Guide for the Fire Protection of Buildings as a basis for providing guidance on what they require for property protection purposes, subject to a broad based risk assessment. In respect of external composite panels, these must be suitable for the intended end use application and should either have non-combustible cores or be LPCB approved to the appropriate requirements of LPS 1181 (see paragraph 3.11) and fully satisfy insurers fire resistance requirements (insulation and integrity) through appropriate testing.”

– ABI Technical briefing on sandwich panels: Clause 4.4, page 11

This paragraph clearly places suitably tested and certified insulated panel systems on a par with those that have a non-combustible core with a test classification according to the requirements of Approved Document B of ‘limited combustibility’.

  • Sandwich panel systems approved by LPCB to LPS1181 will not make a significant contribution to a fire. ABI Technical briefing: Section 3.5,
    page 6
  • Panels satisfying the requirements of LPS1181 will not make a significant contribution to fire growth. ABI Technical briefing: Section 3.11,
    page 8
  • For new buildings, serious consideration should be given to the use of the better performing LPCB approved sandwich panels to LPS 1181 for external claddings in any of the following circumstances taking account of the other factors identified as critical to fire ignition risk and spread. ABI Technical briefing: Section 4.2, page 10

This recommendation refers to higher risk situations such as high financial exposure, hazardous processes, high-risk fire loads etc.

F M Global

F M Approvals, a fully owned subsidiary of FM Global is an insurance approval company which proactively supports good building design by means of a number of written documents and the approval testing of materials and services through the Factory Mutual Research Corporation.

FMRC approvals procedures encompass the testing of specific physical characteristics, e.g. wind uplift; foot traffic, in addition to fire characteristics.

In the case of insulated panels the standard used for the assessment of fire performance is FM 4880 ‘Approval Standard For Class 1 Fire Rating of Insulated Wall or Wall and Roof/Ceiling Panels, Interior Finish Materials or Coatings and External Wall Systems’. The latest version of this Standard was published in May 2010. This certification is based on a number of tests ranging from small scale to large scale covering the following.

  • Density;
  • Heat of Combustion – ASTM D3286-91a;
  • Ignition Residue – ASTM D482-95;
  • Flammability Characterisation – 50kW FM Approvals Flammability Apparatus;
  • Surface Burning Characteristics – ASTM E84; and
  • Room fire test – UBC 26-3

In addition to the above it is a requirement of approval to Class 1 with No Height Restriction that the material is capable of passing the FM Approvals 50ft High Corner Test For certification ‘the assembly shall not support a self-propagating fire which reaches any of the limits of the 50ft (15.2m) high corner test structure as evidenced by flaming or material damage and ignition of the ceiling of the assembly in the 50ft (15.2m) high corner test shall not occur’. Alternatively approval to Class 1 with No Height Restriction can be achieved by appropriate performance in the FM Approvals 16ft parallel panel test.

Links:

ABI Technical Briefing