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Last edited 03 Jul 2025

Types, tests, standards and fires relating to external cladding

[edit] Introduction

Now firmly settled into the 8th year since the tragic Grenfell Tower fire, which claimed 72 lives, there remains an unsettled feeling, a continued certain level of unease. The recent fire that broke out in the Dubai tower one day before the anniversary of Grenfell highlighted why so many factors remain unresolved internationally as well as nationally.

As of the end of May 2025, the UK government' Building Safety Remediation monthly data release reports an extra 124 buildings since April 2025, amounting to an extra 1,379 buildings since the first report. A total of 5,176 high-rise (18 m+) and mid-rise (11-18 m) buildings have been identified with unsafe cladding, with 2,482 (48%) having started or completed remediation works and 1,754 (34%) having completed remediation works.

These reports give updates on what it considers all unsafe external wall cladding systems on buildings, which means reporting on buildings with Aluminium Composite Material (ACM) but also other Non-ACM cladding materials, which might include High-Pressure Laminate (HPL) panels and other Metal Composite Materials (MCM) such as zinc, copper, or steel composites, as well as certain timber cladding.

The government also reports on what it calls non-cladding remediation projects, which are projects where issues lie not with the cladding but with other fire-related defects, such as replacing inappropriate fire doors, fixing missing compartmentation, replacing combustible walkways or balconies, reinforcing low-strength concrete beams to improve structural integrity and fixing any other defect in the scope of the relevant defect definition that is not a defect of the cladding system.

This article tries to look historically at the various types of cladding material, both ACM and non-ACM solutions, when they were first used and when they became popular. Alongside this we have tried to create an extensive list of all fires where the cladding material had been mentioned in the reports as being either a significant contributing factor, a contributing factor or a potentially contributing factor (often awaiting a final report). The list remains a starting point of references for the wiki and a work in progress that can be added to, edited or updated by users.

[edit] Key standards

[edit] BS 476 Fire tests on building materials and structures.

The BS 476 standard, is now being phased out. It was first published in 1932, established a unified method for assessing the fire performance of construction elements. It initially focused on two aspects: reaction to fire (early fire behaviour such as spread and growth) and fire resistance (later-stage behaviour related to structural integrity). Over time, the standard evolved into a series, with each part addressing specific elements—for instance, BS 476: Part 22 covered non-load-bearing components, used alongside Part 20 for general fire resistance requirements. The series was regularly updated until the early 1990s, when development slowed due to the introduction of the EN standards aimed at harmonising regulations across the EU. MHCLG have confirmed the British Standard BS476, which relates to reaction and resistance to fire, will begin to be removed from Approved Document B from its next amendment then phased out completely.

[edit] EN 13501 Fire classification of construction products and building elements

The EN 13501 series of classification standards was developed by the European Committee for Standardisation (CEN) in response to the European Commission’s mandate to create a harmonised system for testing and classifying construction products under the Construction Products Directive (CPD), later replaced by the Construction Products Regulation (CPR) in 2011. The system aimed to facilitate trade and standardise technical language across EU member states. The key difference from the UK’s BS 476 system lay in how scope extension is handled: BS 476 relies on expert judgment, while EN uses standardised rules. Despite EU origins, EN 13501 is relevant to UK building regulations post-Brexit. Parts to the standard include:

EN 13501-1: Reaction to fire tests for construction products. The Euro class system categorises materials into classes A1 to F based on their reaction to fire, with A1 being non-combustible and F being highly flammable. It also includes additional classifications for smoke production (s1 to s3) and flaming droplets/particles (d0 to d2).
EN 13501-2: Fire resistance tests for construction products.
EN 13501-3: Fire resistance tests for products used in building service installations.
EN 13501-4: Fire resistance tests for smoke control systems.
EN 13501-5: Classification using data from external fire exposure to roofs.
EN 13501-6: Reaction to fire tests for electrical cables.

[edit] BS 8414 Fire performance of external cladding systems

Standard governing the large-scale fire test method designed to assess the fire performance of external cladding systems on buildings. Developed to replicate realistic fire conditions, the test evaluates how cladding materials—including insulation and other components—behave when exposed to fire, particularly whether they contribute to the vertical spread of flames beyond the point of origin. The test involves constructing a full-scale, two-story test rig that simulates a building façade. A controlled fire is ignited at the base, simulating a fire breaking out of a window. The system is then monitored for flame spread, heat release, and falling debris, offering a comprehensive understanding of how the cladding would perform in an actual fire.

BS 8414 has two parts. BS 8414-1:2020 addresses cladding systems fixed to a masonry substrate. BS 8414-2:2020 covers systems attached to a structural steel frame. Both tests aim to evaluate the fire safety of cladding systems in configurations common to modern construction.

[edit] BR 135 Fire Performance of External Thermal Insulation for Walls of Multistorey Buildings

Is a key guidance document that supports fire safety in building design, specifically addressing non-loadbearing cladding systems commonly used for improving energy efficiency in multi-storey structures. It works alongside the BS 8414 large-scale fire test method by providing the criteria used to assess whether a cladding system passes or fails the test.

The primary objective of BR 135 has been to ensure that cladding systems do not promote excessive fire spread, whether the fire originates inside a building and breaks through a window, or starts externally. The document defines how fire spread should be evaluated using data from thermocouples and other monitoring tools during BS 8414 tests. It outlines performance thresholds for parameters like flame spread and temperature rise, forming the basis for regulatory decisions regarding the use of specific cladding systems. It plays a vital role in fire safety regulations and is often referenced in determining compliance with UK building codes.

Over time, BR 135 has been updated to reflect evolving building technologies, materials, and lessons learned from fire incidents, such as Grenfell Tower. While the third edition of BR 135 (Fire performance of external thermal insulation for walls of multi-storey buildings) is still relevant, it's important to understand its limitations and the current regulatory landscape. BR 135 provides guidance on fire performance of cladding systems, but it has not been reviewed since the 2020 versions of BS 8414 Parts 1 & 2. This means the third edition of BR 135 cannot be used for classification with the 2020 published versions of BS 8414. Therefore, while BR 135 principles may still apply, designers and building owners should consider the current regulatory climate and conduct necessary risk assessments

[edit] Other standards

Here is a list of other standards we have found that may also be relevant:

BS EN 13169 covers expanded perlite products used in insulation, outlining their performance characteristics.
BS EN 17237 specifies the characteristics and performance requirements for with renderings, designed to be used for thermal insulation in buildings. It covers the system as a whole, including the thermal insulation product, the rendering system, and the way they are combined.
EAD 040427-00-0404 is a European Assessment Document (EAD) that specifically addresses kits focusing on mortar as insulation product and renderings or discontinuous claddings as exterior skin.
BS 8104 deals with the assessment of wind-driven rain and is relevant for ensuring the weather resistance of cladding systems
ETAG 004 & ETAG 034 are European Technical Approval Guidelines that provide a framework for assessing the performance of ETICS, including resistance to artificial weathering and thermal shock.
BS 6093 provides guidance on the detailing of openings, penetrations, and movement joints to minimise the risk of rainwater ingress in building elements.
BS 5422 specifies the performance requirements for thermal insulating materials used in various building applications, including ETICS / EIFS/ EWI.
BS EN ISO 17738-1-4 materials, performance characteristics, requirements for individual components such as the insulation boards, base coat, and reinforcing mesh. Installation guidance, water-resistive barriers, design requirements, specifications, details on interfaces, joints, and flashings and site verification.
BS EN 13163 covers requirements for factory-made EPS products, potentially used in cladding solutions.

[edit] Types of cladding

Here are some brief descriptions of what might be referred to as contemporary cladding types, that have been used on a variety of both high rise and low rise buildings. It is important to note that the specification of many of these cladding types are not fixed, that is to say there are often slight variations in the specification within each type. For example some ACM products use chemical based cores with fire retardants and some without, with some have mineral based cores.

In terms of the product make up variations may exist in terms the combination of external face material, core material, internal face material, as well as the design or form of the panelling, the use of compartmentalisation and fire breaks as well as the details of the specific build-up and how one system is used in combination with another, such as rain screen cladding with a different insulating product behind (and indeed variations in how that insulation itself is fixed).

The specification of the whole wall build-up from external face to internal wall can therefore be complex, with a variety of factors impacting safety. This list merely tries to list fires where wall build-ups were questioned in the media reporting, it is not a definitive list as such and any conclusions drawn from specific fires listed should be based on further research on a case by case basis, looking at the specific make up of the whole wall build comprised of different products and any other external factors. .

[edit] ACM type cladding

Metal composite material (MCM) or more specifically aluminium composite material (ACM) with a polyethylene core, a type of combustible cladding, was first developed in Germany during the 1960s. Initially used in mattress production, it was later adopted for building facades due to its appealing characteristics. The original patent for Alucobond Aluminium Composite Panels (ACM) was filed in 1971 by Alusingen, in collaboration with BASF, under the company name Alusingen (later Alusuisse) with a patent term of 20 years.

This new product ACM was a lightweight, easy to handle, relatively inexpensive, attractive option for modern construction. However, the benefits come with a significant drawback: a high fire risk. It is clear today that the product held significant risks especially when used in combination with other combustible materials or installed in certain ways for example with gaps behind facilitating fire spread.

The original patent for Alucobond Aluminium Composite Panels (ACM) was filed in 1971, meaning it expired in 1991. After the patent expiry, other manufacturers like Alcoa (Reynobond), Mitsubishi (Alpolic), and Etem (Etalbond) entered the market. Reynobond 55 utilised the original ACM technology patent from 1971, and the name “Reynobond” was officially trademarked in the U.S. on October 4, 1988, with production of Reynobond panels (including the 55 model) commencing around 1989.

Warnings about the fire risks associated with ACM cladding have been present since the 1990s. Despite this, it continued to be widely used even with some serious fire incidents occurring worldwide, though in some countries, regulations did prohibit the use of ACM with polyethylene cores on tall residential and public buildings. Today this approach of limiting use on tall buildings has also been taken in the UK, after the tragic Grenfell Tower fire. However, addressing the risks of existing buildings with such cladding remains an ongoing major challenge, involving complex and costly remediation efforts. See articles Accelerating the remediation of buildings with unsafe cladding in England.

Indication is that some ACM cladding products are available with with fire resistant cores and potentially non combustible cores, some manufacturers use initials after their product such as PE (indicating a polyethylene core) or FR (indicating a fire resistance core which might be mineral based or chemical based with a fire retardant). Here are some of the relevant standards we found.

[edit] ETICS / EIFS / EWI type cladding

External Thermal Insulation Composite System (ETICS) also called Exterior Insulation and Finish System (EIFS) or simple Exterior Wall Insulation (EWI) systems are non-load-bearing cladding systems for exterior walls that provide insulation, weather resistance, and a decorative finish. They are multi-layered systems, sometimes misleadingly called synthetic stucco, with insulation boards, a reinforcing mesh, a base coat, and a finish coat, usually a decorative cement render (hence the reference to stucco), the terms are used in different regions.

Because the systems are multi layered there can be a variety of types with the major variation often being in the material of the rigid insulation board, which may be called PB EIFS using expanded polystyrene (EPS), PM EIFS using extruded polystyrene (XPS), phenolic resin insulation, mineral wool (MW), or graphite-enhanced EPS (G-EPS). It is the difference in specification of the rigid insulation that many critics say is key to the products fire resistance, with EPS suggested as being the worst in performance under fire situations and MW the best, although in terms of thermal performance the opposite is true with thicker build-up required by MW.

Other variations in the types of ETICS or EIFS lay in how the system is fixed to the external walls, which can be through adhesive or through a variety of framing systems. Finally the finish layer may also vary considerable with the use of materials such as a thin render finish as described but also, brick slips, stones slips, tiles, glass, metal (MCM or ACM) and potentially timber. Here are some of the relevant standards we found.

[edit] GRP type cladding

Indication is that Glass Fibres were first demonstrated in 1893, by an American glassmaker, Edward Drummond Libbey, at the World’s Columbian Exposition in Chicago which ran from May until October that year. Such fibres had been produced earlier but as individual examples and not mechanised. They had also been found naturally, glass formations of cooled lava stretched into thin strands, near lava fountains, cascades, or lava flows, known as Pele's hair (after the Hawaiian goddess of volcanoes) or witches' hair'.

What is now referred to as glass wool was first invented in the 1930s by researchers at Owens-Illinois, led by Games Slayter, who could produce large quantities of glass fibre efficiently and cheaply, with the first commercial product of available in 1936. Owens-Illinois also later used this fibre technology to patent a glass fibre reinforced polyester resin product which marketed under the trade name Fiberglas. Owens-Illinois later partnered with Corning to produce and refine the material, which became a significant product for both companies

Glass Reinforced Plastic (GRP) rain-screen cladding was not patented as a specific product, but the underlying technology of glass fibre reinforced plastic was developed in the 1930s. The combination of glass fibres and polyester resin, which forms the basis of Glass Reinforced Plastic (GRP), was pioneered by researchers like Eric Owen from Owens-Illinois in 1936. Commercial production of the material, including its use in building applications, followed in the 1930s and 1940s.

There is very little detail documentation about façade fires from 1971 to 1991, with the first major documented cladding fire being Knowsley Heights, Merseyside, UK in 1991, which used what was called a glass reinforced plastic (GRP) rain-screen cladding. The cladding was used as part of a refurbishment project , carried out in 1998 and aimed at addressing damp issues in the building, using a Class 0 GPR cladding, a "combustible polymer material" (in the Grenfell inquiry report).

[edit] HPL type cladding

High Pressure Laminate (HPL) panels are a form of cladding typically manufactured by layering sheets of wood or paper fibre with a resin and bonding them under heat and pressure. They sometimes include additional chemicals to provide fire retardant properties and are available in a wide range of colours and finishes. Panels which incorporate fire retardant chemicals are sometimes referred to as “FR grade” and these will typically achieve Class B-s1, d0. Panels manufactured without fire retardant chemicals are typically Class C or D, depending on the thickness of the panel.

The Belgian chemist Leo Hendrik Baekeland patented Bakelite in the early 1900s, following this he started to experiment with melamine formaldehyde and resin absorption into papers. Indication is that this led to the development of laminate sheets under high pressure with phenol resins in panel form, by the 1920s these saturated paper with phenol-formaldehyde resins hardened between steel plates were available commercially mainly for interior and furniture uses. By the 1950s layers of core paper were saturated with phenol resins and décor paper saturated with melamine resins giving a wide variety of finishes, by the 1960s similar High Pressure Laminates (HPLs) were considered suitable for external use

The first International standard ISO 4586-1, was created in 1987 an initial standard establishing a classification system for high-pressure decorative laminates based on their performance and applications. The EN 438-1:1991 was developed for decorative high-pressure laminates (HPL) sheets based on thermosetting resins as a multi part standard, with parts EN 438-5, 6 and 7 concerning themselves with external grades of HPL.

ISO 4586 was revised in 2004 to became multi-part standard with ISO 4586-1 providing an overview and guidance on the entire series, ISO 4586-2 focusses on testing methods and the others ISO 4586-3,4 and 5 addressing specific types of laminates. These were revised at various points in 2015, 2018 and 2024. EN 438 was introduced as a multi part standard with: EN 438-1 covering general classification and specifications for high-pressure decorative laminates. EN 438-2 focussing on properties and tests like resistance to staining, light fastness, and dimension stability. EN 438-3 addresses laminates with a thickness of less than 2 mm, intended for bonding to supporting substrates. EN 438-4 covers compact laminates with a thickness of 2mm and greater. EN 438-5 and 6 covers exterior-grade compact laminates with EN 438-7 covering compact laminate and HPL composite panels for internal and external wall and ceiling finishes. Various sections from EN 438 have been updated in 2005, 2009, 2016 and 2018, which is the latest version published in January 2019.

[edit] MCM type cladding

MCM cladding was introduced after ACM cladding systems, offering a variety in finishes with metals such as zinc, copper, steel, titanium or composites being used. The principles are the same as ACM in that sandwich panels, with two metal outer layers and an inner core are created as flat or shaped units and act as a cladding system. As with ACM systems the type of core used can be critical with specifications varying from zero combustibility mineral based cores to low combustibility to high combustibility products. Alongside this consideration needs to be pais to the role of compartmentalisation, fire breaks and use in combination with other products such as external insulation.

[edit] Timber type cladding

There are historically many fires associated with the use of timber, which is why taller buildings with timber cladding are quite rare. However there is an increasing popularity in massive timber structures buildings using using examples such as Cross Laminated Timber (CLT) or Encapsulated Mass Timber Construction (EMTC). There are also increasingly examples of low density fibre boards or batts used as insulation for buildings, some argue the main difference in terms of fire risk is how such timber products burn rather than is they burn.

The fire rating for larger profile product comes from treatment of the timber face along with char ratings, in which timber may burn at the surface but so long as the profile is deep enough the structural integrity remains as char that forms on the outer surfaces effectively creates a black insulating layer that protects the unburnt timber beneath. However in the case of laminated timber, under fire conditions the adhesive layers can delaminate, which means that a protective char layer that has been created can potentially fall off which exposes fresh, unburnt timber to the fire. Other issues which also apply to low density insulation products can also be that because timber burns more slowly, some arguments say it can continue to smoulder after the fire has been extinguished, which can risk reigniting or gradual reduction of structural integrity.

In the use of low or medium density fibreboard bats, as rigid insulation boards made from fine timber cuttings, indication has been that, although lower density than massive timber, these thicker boards first burn slower than plastic blown insulants and might also benefit from charring which prevents total combustion. Although this can vary depending on the details of the cladding for example if it has a cavity behind.

We have looked for specific examples of fire in modern buildings that employ these techniques and technology but have not found any. This does not mean that they do not exist, please add to the list below with references if there are examples that should be added.

[edit] Example of fires by year group

Below is a reverse timeline highlighting major fires involving cladding of different types that have occurred globally, some are high rise buildings some are not. Many of these examples mention specific cladding materials as being key contributing factors to the fire, whilst others cladding is mentioned, but not explicitly indicated as being responsible. This list is extensive but not exhaustive, as there are potentially many smaller fires that have not been well publicised. However with over 50 examples these highlight how many fires have taken place historically and as such that certainly some of the risks of said materials were known, they don't highlight why such materials continued to be used.

[edit] Fires between 2021-2025

2025 June 14 – Marina Pinnacle, Dubai, UAE A 67story residential tower fire lean on cladding; no reported injuries amongst nearly 4,000 evacuees.
2024 February 22 – Valencia Residential Complex, Spain. 14-storey Alucobond ACM (polyethylene core) facade caught fire rapidly; 10 deaths, 15 injured
2023 April 15 – AlRas Residential Building, Dubai, UAE. Fire spread via non-compliant ACM cladding; 16 deaths and 9 injuries.
2021 - Torre dei Moro (Milan) & Torre Ambar (Madrid), Italy & Spain. Fires in ACM-clad towers widely reported; flames rapidly engulfed upper floors of both.

[edit] Fires between 2016-2020

2020 - Chongqing fire, China. Ignited by flames from the balcony of the 2nd floor, and the flame spread upward to the 30th floor within just a few minutes.
2019 June 9 – Samuel Garside House, Barking, London, UK. Woodclad balconies ignited from a barbecue, destroying 10 flats; no deaths, 2 injured. Although under 18m tall, combustible cladding contributed to rapid fire spread
2019 November - Bolton Cube fire, UK. A smaller building (<18m) with combustible façade panels caught fire quickly. “The incident also brought home the danger of leaving flammable cladding on buildings.” 217 people escaped and there were no serious injuries. https://www.bbc.com/news/uk-england-manchester-53597167
2017 Cvjetno naselje student dormitory fire, Zagreb. Fire started on the roof of the lower building. Combustible thermal insulation of the façade system and a strong wind definitely contributed to the fast spread of flames and smoke on the façade. https://www.grad.unizg.hr/images/50014277/Fire%20Protection%20of%20Facades.pdf
2017 July 14 – Marco Polo Condos, Honolulu, USA. High-rise fire damaged over 200 units; 4 deaths, 13 injured—cause undetermined but external factors suspected.
2017 June 14 – Grenfell Tower, London, UK. A fridge fire escalated into a catastrophic blaze spread by polyethylene-core ACM cladding, killing 72 and injuring 74
2016 - Astar Court, Mount Pleasant Hill, E5 (listed by the Grenfell Inquiry)
2016 - Neo Soho, Jakarta. Spread up multiple floors during construction through ACM cladding.
2016 - Ramat Gan high-rise, Israel. A minor internal fire rapidly spread externally via combustible insulation panels.