Composite Panels & Exterior Cladding Systems

INTRODUCTION

This guidance note is designed to provide Consultants with general information regarding ‘composite panels’ and how to treat such panels as regards risk assessment and reporting. Exterior cladding systems and how these are to be assessed are also covered in this document.

Any guidance given in specific Client Service Instructions takes precedence. In this respect, attention is drawn to RSA Global Consulting document Composite Panels: G012 – A Risk Control Guide to Composite Panels and Exterior Cladding Systems, which must be adopted when conducting RSA surveys.

DEFINITIONS

Composite panels are a pre-fabricated insulated system delivered to site ready for installation, having an internal metal skin (some are available with plastic or fabric internal lining), an insulation core and an outer metal skin. These have already been bonded together by the manufacturer. Whilst having their origins in the food industry and, in particular cold storage applications, composite panels are now widely used in the construction of commercial, industrial and other buildings.

The most common types of composite insulation employed are as follows, with potential greatest concern first:

Expanded Polystyrene (EPS) – Highly combustible
Fire Retardant EPS - Combustible
Polyurethane (PUR) - Combustible
Polyisocyanurate (PIR) (Standard) – Combustible
Polyisocyanurate (PIR) (Approved) – Will withstand fire for longer but ultimately combustible (see note)
Modified Phenolic – Combustible but with a good degree of fire resistance
Foamed glass - Non Combustible
Glass Fibre - Non Combustible
Mineral Wool - Non Combustible

Note: - For normal purposes, approved panels have been tested and approved by the LPCB or FM.

Typical Composite Panels

A site assembled built-up system, typically comprising inner and outer plastic coated profile metal skins incorporating an insulation layer. In the vast majority of applications, mineral fibre insulation is employed with the result that these have generally been regarded with minimal concern. However, fire stopping in multi-storey applications can be of importance and is a specific requirement of Building Regulations. Such systems would not normally come under the recognised definition of “composite panels”.

Typical Site Assembled Built-up Cladding Systems

FIRES INVOLVING COMPOSITE PANELS

Most of the earlier and larger fires involved EPS cored panels. However, some Insurers have adopted a mind-set that all combustible cored panels will react in a similar fashion, even though this is not actually the case. It is true that a relatively small fire can grow disproportionately and with the core adding to the site fire load a much greater loss would follow. Typically, whatever the risk, Insurers will regard these sites with a 100% EML and hence possible capacity problems.

Fires rarely start within the panels. A fire in, or outside, the building in proximity to the panel will cause the panel face to heat up. As the temperature of the metal sheet increases the insulation draws away from the heated surface causing an air gap within the panel. This is known as delamination. This continues as the temperature rises until the insulation material reaches its auto ignition temperature and begins to burn. We now have a self-propagating fire in the core of the building cladding. Since it is the insulating core of the panel that gives it rigidity, the collapse of the cladding follows rapidly, exposing further core to the fire.

Enhanced exposure exists if the panel surface integrity is damaged or punctured. Typically, the metal faced panels will offer a good degree of protection against flame, often referred to as a zero rated panel. If this panel is drilled or modified on site, the surface becomes unrated and exposes the core more rapidly. Additionally, if exposed to damage from forklift trucks, for example, this exposure is increased.

Fire Officers are concerned with the speed at which these fires spread. Intense heat released on the delamination of the panels and the toxic products of combustion resulting from a fire in this type of panel makes conventional methods of firefighting difficult. Composite panels themselves put fire fighters at substantial risk from structural failure, often with catastrophic results. It is difficult to predict the path of spread through voids particularly when large panels are used. As the fire spreads through the core, delamination results with the outer covering peeling back increasing the rate of propagation. Firefighting techniques then become defensive trying to restrict spread to other buildings or beyond true fire breaks. Due to the fabrication of the panel, a core fire cannot successfully be fought as the panel is designed to be impervious to water penetration.

‘APPROVED’ PANELS’.

LPCB and FM approved PIR cored panels are typically more acceptable to Insurers.

Dependent upon their application, different testing criteria is applied for panel approval. For the purposes of evaluation, the FM testing has similar characteristics to the LPCB testing, and can be regarded as equivalent. There are 2 LPCB testing regimes comprising LPS 1181 & LPS 1208.

LPS 1181

LPS 1181 consists of the following parts:

LPS 1181: Part 1 Requirements and tests for built-up cladding and sandwich panel systems for the use as the external envelope of buildings.

LPS 1181: Part 2 Requirements and tests for sandwich panels and built-up systems for use as internal construction in buildings.

(Reference by LPCB to the term “built-up cladding systems” is unfortunate and does not alter the objective that the tests are focused towards factory produced composite panel products.)

Within LPS 1181 are a number of classifications and these are summarised as follows:

Cladding systems used for the external envelope of buildings are tested to LPS 1181: Part 1. Products that pass the test are graded into 2 classes:

o Grade EXT-A** - A product that satisfies both the requirements of LPS 1181 and also demonstrates fire resistance through a fire resistance test as specified in LPS 1208 (detailed below). Such products meet the requirements for separating elements of construction. (** represents in minutes, the LPCB grading of insulation achieved during the fire resistance tests.)

o Grade EXT-B – A product that satisfies LPS 1181 only.

Sandwich panels and built up systems used internally are tested in the large-scale test in LPS 1181: Part 2. Products which pass are graded into 3 classes:

o INT-1 – A product that achieves a minimum fire resistance of 60 minutes in respect of both integrity and insulation.

o INT-2 – A product that achieves a minimum fire resistance of 30 minutes in respect of both integrity and insulation.

o INT-3 – A product which passes LPS 1181: Part 2 but has no fire resistance.

LPS 1208

LPS 1208: LPCB test and performance requirements for walls, cavity barriers, floors, and roofs defines the test and performance requirements to satisfy the fire resistance requirements for compartmentation given in the LPC Design Guide for Fire Protection of Buildings.

The results of this test are indicated by a Grade of FR30, FR60, FR90 etc. which is the fire performance achieved in the test in respect of both integrity and insulation. In cases where the integrity and insulation performances differ, the lower figure governs the Grade which is applied. When specifying composite panels in accordance with LPS1208, reference must also be made to the maximum unsupported spans, as detailed in the approval’s tables within the LPCB Red Book, to ensure correct integrity performance.

It should be noted that FM approval is also interfaced with occupancy, with a caveat in the standards that if a substantial fire load is present sprinkler protection would be required.

Panel identification with particular reference to LPCB or FM approval can be problematic. Best advice to Policyholders would be to ensure that panel specifications are retained on file for future reference, although this is often not the case. Kingspan, the largest UK manufacturer of composite panels, hold an extensive project register which can be used for this purpose and a call into their offices in Holywell, Flintshire on 01352 716100 quoting the post code of the premises in question will on occasions obtain a result.

Since the middle of 2002, all panels produced by Kingspan carry UV ink identification markings as illustrated below on the lining (internal) side which can normally be found at 1.5m intervals along the female joint, 100mm in from the edge. For roof panels, markings are applied to the crown overlap.

It will be noted that whilst the makings confirm LPCB approval, they do not differentiate between LPS 1181 and LPS 1208.

For the purposes of the RISCAuthority (InFiRes) Categories of Building Construction, panels which have achieved LPCB or FM approval are to be deemed non-combustible.

NON COMBUSTIBLE PANELS

Glass Fibre and Mineral Fibre panels are non-combustible. They are typically considered to be more expensive. They are heavier and can require additional steelwork to support them. This increases the cost of using such panels, although when comparing with PIR LPCB Grade A panels, in a lot of instances this may not be regarded as significant.

The LPCB do not offer a Non-Combustible rated panel as test criteria is time dependant, for example if the test is for 240 minutes, it will be stopped at 240 minutes and that is the approval given. FM do have a Non-Combustible designation, and to date only mineral wool has satisfied this fire test.

Within food associated risks considerable concern has been voiced about fibre contamination, this is a risk, but available data shows that the fibres pose no human health hazard. Additionally, with safe systems of working and good management standards, it should not be considered an undue exposure as we would not anticipate clients working on panels in an uncontrolled method or with food/product directly present. A ‘Permit to Work’ system should overcome any problem in that respect.

One concerning aspect does remain which is that the panel manufacturers do not recommend use in a negative pressure envelope, e.g. Cold Store.

Other rumours are of delamination when not involved in a fire, although we would advise that any panel suitably installed and stitched will not delaminate. We have also had concern expressed that there is a risk of infestation by insects where the looser mineral material is used. We have no evidence to substantiate this.

MODIFIED PHENOLICS

Modified Phenolics are relatively new and therefore may be considered unproven. Under test conditions they have been rated as non-combustible. They offer excellent insulation quantities and would appear an ideal solution. Unfortunately, they are in very limited production, are restricted in individual panel size and hence are proportionately expensive.

MANAGING THE RISK

The following guidance goes some way to reducing the risks involved with combustible composite panels. However, in some instances these measures may alone be insufficient, in which case a firm commitment to a panel replacement programme and/or or sprinkler protection may be required.

In order to prevent combustible insulation from exposure to ignition sources, facings and joints should be maintained and kept in good condition. This is to retain the degree of fire resistance presented by the facings and to reduce the risk of fire spread to any void behind the panel. Regular inspections are needed to be made with written records maintained.
Penetrations through panels should be avoided wherever possible.
Repairs to composite panels should never involve the use of welding or other obvious ignition sources. Likewise, such “hot work” should not be allowed in the vicinity of composite panels, unless they are protected by non-combustible or purpose made blankets, drapes or screens. A Hot Work Permit system should also be in place. Any work on panels should be subject to a risk assessment.
It is of vital importance that storage of combustible materials, such as timber pallets or plastic crates, in yard areas is not against or within risk of walls containing composite panels. Ensure a distance of at least 15 metres from buildings with hazardous processes, 10 metres from other buildings.
Forklift truck battery charging should be carried out well away from composite panels. Preferably this should be in a separate building or area.
Electrical inspection and testing should be carried out annually on electrical equipment and cabling in the vicinity of composite panels. Thermal inspection of the systems at regular intervals is a cost effective and proactive tool in reducing exposure from electrically generated fires.
Where possible, services should not pass through insulated composite panels. If this is unavoidable, gaps around those services should be fire stopped to protect the insulation material. All electrical cables passing through insulated panels should be enclosed in conduits. Ideally all holes etc should be precast at panel design and order stage to ensure greater panel integrity.
Direct mounting of machinery and electrical equipment to panels should be avoided. If this is unavoidable, steps should be taken to prevent the exposure of the insulation, and where necessary fire stopping should be in place around the fixing.
Make cleaning and preventative maintenance of food processing equipment a regular discipline. Internal inspection and cleaning of flues and extract ducting should be a regular occurrence.
If a heater flue or other potentially hot trunking passes through panels, this must be installed in a non-combustible insulating collar not less than 40mm thick. Proprietary sleeve systems that can achieve 60 minutes fire resistance in terms of integrity and insulation are also acceptable. Gaps between the collar and panels should be filled with mineral fibre or other suitable non-combustible material. In the case of modern plant, double skinned, insulated flues may be anticipated providing enhanced protection. However, the presence of such flues does not remove the need for cut back and collaring as detailed.

The importance of ensuring correct attention to this aspect is paramount and where the Consultant is unclear as to the precise cut back and protection requirements needed, an alternative risk improvement wording is available referring the Policyholder back to the manufacturers of the heater, oven or other item of plant for guidance.

(Note: Where dealing with flue penetrations through “approved” panels, the advice of the BRE has been that these should be dealt with in the same manner as if combustible, owing to the fact that the longevity of the “fire safe” properties of an “approved” panel may deteriorate over a period of time when subjected to constant heat.)

11. The routing of pipes containing steam or hot fluids through panels should be avoided.

12. Hazardous processes (such as deep fat frying) should be located well away from composite panels. The preferred solution is that all hazardous processes be compartmented with walls and, where appropriate, ceiling construction to a level of fire resistance commensurate with the risk. Doors and other openings should be of a similar fire rating and, where required, should be fitted with automatic closers.

13. Where appropriate, hazardous process equipment should be fitted with automatic fire suppression systems.

14. Where there is an accessible celling void created by composite panels, storage should be prohibited from these areas. Designated walkways should be provided in celling voids as an aid to inspection. Access to such areas should be restricted.

15. Carry out robust fire risk assessments in accordance with the Regulatory Reform (Fire Safety) Order 2005 to ensure that fire risks are reduced to a minimum. The construction materials present should form part of the risk assessment, as regards their combustibility and contribution to fire growth.

When considering the possibilities of panel replacement, it should be kept in mind that partial replacement may result in thermal bridging owing to the variance in thermal performance of different types of panels; this can give rise to the formation of condensation, which in the case of the food industry is unlikely to be tolerated.

STANDARD RISK IMPROVEMENT WORDINGS

Various ‘standard’ RiskSTOP risk improvement wordings are available to consultants and these are to be used wherever possible.

COMPOSITE PANEL WARRANTIES/CONDITIONS PRECEDENT

Consultants need to be aware of any Warranties or Conditions Precedent applying to a policy, and if the Policyholder is in compliance or not.

PANEL IDENTIFICATION

Consultants are to make every endeavour to identify the type of panel(s) encountered with reference to insulation material and LPCB/FM approvals status, details of which are to be included in the report. However, where this proves impossible, the Consultant must assume the insulation core is combustible, and the report written accordingly.

Risk improvement measures should not be put forward to provide information on the type of panel, but Underwriters should be advised to seek such information from brokers/policyholders.

FURTHER REFERENCE

1. EPIC (Engineered Panels in Construction) has published an extensive guide entitled: Insulated Panels - The Fire Safety Order 2005 (revised April 2015). Section 5 of this publication provides excellent guidance on the subject of panel identification.

2. RSA Global Consulting document Composite Panels G012 – A Risk Control Guide to Composite Panels and Exterior Cladding Systems. As previously mentioned, this must be adopted when conducting all RSA surveys.

EXTERIOR CLADDING SYSTEMS

The hazards associated with external cladding/rainscreen systems were tragically and extremely vividly illustrated by the fire at Grenfell Tower in June 2017

The exterior cladding is reported to have been a rainscreen system of Aluminium Composite Material (ACM), comprising of aluminium sandwich panels with a 3mm polyethylene core, a 50mm ventilated cavity and a 150mm polyisocyanurate insulation, fixed to an existing prefabricated reinforced-concrete façade.

Both old and new buildings may be over-clad in materials to both enhance them aesthetically and improve their thermal performance. Common methods, include Rainscreen Cladding Systems and Bonded Cladding Systems known as ETICS (External Thermal Insulation Composite Systems). Both types of system feature a substantial layer of insulation material attached directly to the walls of the building, which may be brick, concrete, or a lining board. Bonded cladding systems provide weather protection using a cement render or other exterior facing over the insulation. Rainscreen cladding systems use a panelling system held proud of the insulation to allow a ventilation void behind.

Aluminium Composite Material (ACM) is the most prevalent form of composite rainscreen cladding This is formed using a core of insulation, which may be a combustible foam plastic, sandwiched between two sheets of aluminium.

Cavity Barriers are installed to limit the spread of fire and smoke in the cavity and insulation behind rainscreen panels and in the insulation layer of bonded systems. For bonded cladding systems using combustible insulation, this is often achieved by the provision of mineral fibre breaks at floor slabs.

With rainscreen cladding systems, fire and smoke may spread more rapidly in the cavity space behind rainscreen cladding than on the outside of the cladding, due the chimney effect. Fire spread hidden behind rainscreen cladding may also lead to delays in detection.

For rainscreen cladding systems provision of cavity barriers is more challenging as these barriers cannot provide complete compartmentation in their normally installed state, as the cavities need to maintain ventilation to prevent moisture build up. To provide a fire and smoke seal in the cavity between brick or block walls and rainscreen cladding, cavity barriers will typically be fitted intumescent elements to seal gaps during a fire. Examples are intumescent strips faced with high tensile foil, which expands to create a fire and smoke seal, or intumescent impregnated sponge barriers with fire and smoke stopping capabilities, which are fitted with a rubberised intumescent strip.

BUILDING REGULATIONS

The position regarding Building Regulations and external cladding systems in high-rise buildings in the regions of the UK is summarised as follows:

England

Arising from Grenfell, in England combustible materials have been banned for use on the external walls of new buildings of at least 18 metres containing one or more dwellings, an institution or room for residential purposes since 21 December 2018, under The Building (Amendment Regulations 2018. The ban included high-rise residential tower blocks, hospitals, residential care homes, student accommodation and dormitories in boarding schools but at the time rooms in hotels, hostels and boarding houses were excluded.

With effect from 1 December 2022, in England the ban has been be extended to the external walls of hotels, hostels and boarding houses of at least 18 metres Although these buildings can be staffed overnight, have multiple escape routes and alarm systems, given that occupants are less familiar with these surroundings, it is considered that there is still a sleeping risk. Balconies, solar panels and solar shading devices attached to the external wall are also included within the scope of the ban with a limited exemption for ground floor awnings. The Regulations will also provide exemptions from the ban for certain materials such as fibre optic cables.

New guidance outlined in Approved Document B also sets out limits to the use of combustible materials in the external walls and balconies for residential buildings of 11 m – 18 m. This is intended to allow designers and developers some flexibility in the use of materials, such as structural timber, on residential buildings below a height threshold of 18 metres, and takes account of existing requirements for the installation of sprinklers in new residential buildings of over 11 metres.

In addition, the Regulations will ban completely the use of metal composite materials (metal composite materials with an unmodified polyethylene core) in the external walls of all new buildings and buildings undergoing building work, regardless of height or use.

Scotland

The Building Scotland (Amendment) Regulations 2022 introduced a ban on the use of combustible materials in external wall cladding systems on dwellings and on other defined ‘relevant buildings’ with a storey at a height of 11 metres or more.

For such buildings, BS 8414 can no longer be used as an alternative means of compliance with building regulations. Combustible materials are defined as anything less than Euroclass A1 or A2 under BS EN 13501-1. Previously, cladding systems on high-rise blocks have either had to use non-combustible materials, or pass a large-scale fire test under BS 8414. The latter will no longer be acceptable as evidence of compliance.

‘Relevant buildings’ include dwellings (houses, flats, maisonettes), places of assembly, entertainment or recreation, hospitals, residential care buildings, sheltered housing complexes and shared multi-occupancy residential buildings such as student accommodation.

In addition, there is a ban on the use of highly combustible metal composite material in an external wall cladding system or used as an internal lining on any building regardless of height.

Separately, as from March 2021 all new-build social homes, flats and shared multi-occupied residential buildings, irrespective of height, are required to be protected by sprinklers.

Wales

With effect from 13 January 2020, combustible cladding on all new residential buildings (flats, student accommodation and care homes) and hospitals over 18m in height. The ban covers the entire height of the building, and will apply to the complete wall assembly and certain attachments to the external wall, including balconies and solar panels.

The ban on combustible cladding will apply to all new buildings, and to existing buildings being refurbished.

Since 2014 there has been a requirement In Wales for all converted and new-build residential property to be installed with sprinklers.

Northern Ireland

Under the Building (Amendment) Regulations (Northern Ireland) 2022, combustible cladding materials can no longer be used in dwellings over 18m in height.

Unlike other regions of the UK, there is no mandatory requirement for such buildings to be sprinkler protected.

PAS 9980:2022 FIRE RISK APPRAISAL OF EXTERNAL WALL CONSTRUCTION AND CLADDING OF EXIXISTING BLOCKS OF FLATS – CODE OF PRACTICE

PAS 9980 is a new code of practice for the fire risk appraisal of external wall construction and cladding of existing multistorey and multi-occupied residential buildings. The code has been developed by a steering group of experts in the fields of construction, fire, housing and safety. It is for use by competent fire engineers and other competent building professionals when undertaking a fire risk appraisal of external walls (FRAEW).

The PAS sets out a methodology to conduct and record fire risk appraisals of external walls, which can be scaled up or down depending upon the complexity of individual buildings. It uses a five-step risk assessment process to assist in the identification of risk factors influencing the overall risk rating of a building, as well as mitigation steps that might improve the risk rating. Not all buildings will require an appraisal, and of those that do, not all will require intrusive inspection.

It also gives recommendations for the competence of professionals completing such appraisals. The standard aims to assist with the ongoing effort to increase the number of competent professionals, by providing knowledge on fire risk arising from various aspects of external wall construction.

The PAS has been issued as a free download and can be accessed here.

IDENTIFICATION OF CLADDING AND RAINSCREEN SYSTEMS

As with composite panels, it is essential that Consultants make every effort to obtain details of all external cladding and rainscreen systems as part of the overall assessment of building construction. Particular regard should be given to the make, type and thickness of the materials/systems employed, including insulation materials and external renders, certified fire performance/product approvals status, and cavity barriers, with a special emphasis on identifying ACM; the relevant details of which are to feature in the report.

In respect of building where combustible cladding has been identified, reference to the status of the required replacement programme must be indicated.

FURTHER REFERENCE

This Technical Bulletin should be cross-referenced with TB45 – Fire Safety in Flats, Houses in Multiple Occupation and High-rise Residential Buildings, with particular regard to ACM cladding/rainscreen systems and the essential precautionary measures that have been established nationally, post Grenfell. .

FIA Publication: Guidance on the Issue of Cladding and External Wall Construction in Fire Risk Assessments for Multi-Occupied Residential Premises.

Further information is also available on the various regional governments’ websites