Fire Risks From External Cladding Panels – A Perspective From The UK

1. Introduction

2. What are the risks?

The mechanisms of external fire spread

3. Fire History in the UK

Development of composite panels

Fires in composite panels

Fires in external cladding

4. Fire History in the UAE

Development of composite panels

Exterior Cladding Fires in the UAE

5. Fire History in China

6. Building Regulations in the UK

Revisions to Building Regulations and Advisory Documents

The View of the Court

Insurers

Firefighters

The Regulatory Reform (Fire Safety) Order 2005

7. Fire Safety Regulation in the UAE

Revisions to UAE Fire Code regarding Exterior Cladding

8. The Conundrum of Existing Buildings with higher risk cladding

 

1. Introduction

New Year’s Eve celebrations in Dubai were marred by the fire in The Address Downtown Hotel and residential building, opposite the Burj Khalifa, the world’s highest skyscraper.  The exterior of the supertall (302m) The Address was consumed in flames and thick black smoke, with more than 40 storeys burning simultaneously at one stage.  Investigations are in hand, but the fire in Dubai’s 18th tallest tower appears to be similar to the fires in the external cladding of the 352m Marina Torch residence (21 February 2015) and of the Tamweel Tower (18 November 2012).  Fire spread in external cladding has been the primary issue not only in these three major Dubai fires, but in others in the Middle East and China.

It is widely suspected that the presence of combustible aluminium composite panels was responsible for the fire spreading alarmingly rapidly up the exterior of The Address.  Composite panels are made of a thin outer metal skin of steel or aluminium and cores of insulating material, which historically have included combustible materials such as expanded polystyrene (EPS) or polyurethane (PUR), but the Dubai fires involved polyethylene (LDPE) cores.

To date there has not been a fatality of a building occupant in the UK associated with composite panels, [1] although 2 firefighters have died.  Neither has there been any fatality in the major cladding fires in Dubai.  Up to now the occupants have had time to escape, albeit with firefighter assistance in several instances, and escape procedures appear to have operated successfully.  This should not be any cause for complacency.  All of the major fires have had the potential for loss of life.

 

2. What are the risks?

The mechanisms of external fire spread

Ignition of composite panels, even those with combustible cores, is not usually instantaneous, but there are various core materials used and they have very different ignition properties.  The early stages of fire development are relatively slow.  It is only in well-developed fires that the combustible cores burn with savage intensity.  However, polymeric core materials such as EPS and PUR will burn at temperatures well below that of a fully developed fire and thus contribute to fire spread.

There is a risk in fire conditions that composite panels are attacked at the joints, or the panels suddenly delaminate and the metal facing falls away, thus exposing the combustible core which then intensifies and spreads the fire.  The sudden increase in fire severity can accelerate the failure of the adjacent panels, so that if a fire does take hold, it can race up or through an entire facade of a building, causing a major hazard to occupants and a major property loss.  Foam cores exposed through damage, fixings or penetrations will ignite sooner than intact panels.  Aluminium has a much lower melting temperature than steel and aluminium facings will fail earlier.

Delaminated panels can fall off the building, raining down hot metal and burning foam insulation on the surrounding area, with risk of personal injury and of starting secondary fires.  In The Address fire, a strong wind blew some of the fiercest flames away from the building, but burning panels drifted up to a street block away and ignited secondary fires on adjacent roofs, despite the fire service’s rapid attendance and their hosing down rooftops from tall aerial platforms.

The mechanisms of external fire spread are succinctly summarised by the author of UK Building Research Establishment (BRE) report BR 135 (see below):

“ The mechanisms by which fire can spread externally include combustible materials and cavities – either as part of a system, or those created by delamination of the system or material loss during the fire.  Once flames enter a cavity they have the potential to travel significant distances, giving rise to the risk of unseen fire spread within the cladding systems.”  [2]

BRE report Fire performance of external thermal insulation for walls of multi-storey buildings (2013) explains the mechanisms of fire spread more fully. [3]

“ 3.1 Initiation of the fire event

This type of fire event can be initiated from a fire occurring inside the building, or by an external fire in close proximity to the building envelope, such as fires involving general waste, or resulting from malicious firesetting.

3.2  Fire breakout

Following the initiation of a fire inside the building, if no intervention occurs, the fire may develop to flashover and break out from the room of origin through a window opening or doorway … Flames breaking out of a building from a post-flashover fire will typically extend 2m above the top of the opening prior to any involvement of the external face, and this is therefore independent of the material used to construct the outer face of the building envelope …

3.3  Interaction with the external envelope

It is at this stage of the fire scenario that the fire performance of the complete external cladding system, including any fire barriers, is critically important.  Once flames begin to impinge upon the external fabric of the building, from either an internal or an external source, there is the potential for the external cladding system to become involved, and to contribute to the external fire spread up the building by the following routes.

3.3.1 Surface propagation

The reaction to fire characteristics of the materials used within the external cladding system will influence the rate of fire spread up the building envelope by way of the surface of the external cladding system.

3.3.2 Cavities

Cavities may be incorporated within an external cladding system, or may be formed by the delamination or differential movement of the system in a fire.  If flames become confined or restricted by entering cavities within the external cladding system, they will become elongated as they seek oxygen and fuel to support the combustion process.  This process can lead to flame extension of five to ten times that of the original flame lengths, regardless of the materials used to line the cavities.  This may enable fire to spread rapidly, unseen, through the external cladding system, if appropriate fire barriers have not been provided (Figure 6).

3.4  Fire re-entry

Window openings or other unprotected areas within the flame envelope provide a potential route for fire spread back into the building.  This creates the potential for fire to bypass any compartment floors that may be present, leading to a secondary fire on the floor above.  If secondary fires are allowed to develop without intervention before flashover occurs, then flames may break out again, thus extending the flame envelope and threatening other openings further up the building, irrespective of the materials used on the building envelope.

3.5  Fire service intervention

Where the external cladding system is not contributing significantly to the spread of fire from one storey to the next, then intervention by the emergency services should prevent continued fire propagation by way of the building envelope.  However, where the external cladding system is contributing to the fire propagation rate, the potential exists for the fire to affect multiple storeys simultaneously, thus making firefighting more difficult.”

 

 3. Fire History in the UK

Development of Composite Panels

Composite panels were developed as a means of providing a cheap, lightweight, weathertight, insulated building envelope, rapidly erected over the interior structure.  Composite panels generally consist of internal and external metal facing sheets, bonded to a core of various alternative insulation materials.  The facings are typically aluminium or steel, with coatings for weather-resistance externally and decoration and hygiene internally.

The most common forms of insulation cores for composite panels in use in the UK at the end of the 20th century, in order of decreasing probability of fire propagation, [4] were:

  • polystyrene (EPS),
  • polyurethane (PUR),
  • polyisocyanurate (PIR),
  • phenolic,
  • mineral fibre.

EPS will initially soften and shrink away from a small flame, but will then melt and burn.  The voids created by melting admit oxygen, which intensifies the fire.  Molten flaming droplets can spread the fire.  All the material between the metal facings is likely to be consumed, leading to loss of structural stability.  At the outset of the fire, development is fairly slow and contained.  In a well-established fire, the material will contribute to the fire development.  Delamination and collapse may be sudden.  EPS was recognised as the worst of the plastic foams in fire conditions.

Extruded polystyrene (XPS) is a thermoplastic product equivalent to the flame retardant grade of EPS, but behaves similarly to EPS in fire conditions.

PUR is combustible.  However, it forms a char layer which tends to inhibit further combustion.  The char layer is relatively fragile.  It may break off to expose fresh combustible foam.  PUR also contributes to fire growth in a fully-developed fire, giving off black smoke and toxic fumes, including hydrogen cyanide above 850oC.

PIR, a variant of PUR having improved fire properties, is difficult to ignite and exhibits a pronounced charring which enables it to withstand fire for longer, but is ultimately combustible.

Phenolic foam is difficult to ignite.  It chars, gives off fumes and burns with black smoke, but flame spread, smoke and toxic fume generation are moderate.

Rockwool mineral fibre, inorganic rock fibres bonded together with small amount of combustible binder, is non-combustible.

In the UK, influence from insurers and technical development within the composite panel industry has led to cores of polymer-cored external cladding panels changing from PUR to PIR to phenolic foam, decreasing the fire hazard.

The fire performance of external cladding panels is not always understood, even by architects and specifiers, and the issues are not straightforward.  The architect / specifier may have difficulty interpreting a composite panel manufacturer’s specification.

Class 1 to British Standard (BS) 476-7 is often cited.  This is a small scale test, which limits the allowable spread of flame over the surface of a construction product after ignition by a pilot flame after 1½ and 10 minutes.  The metal face of a composite panel may resist the application of a pilot flame in such surface testing.

UK Class 0, also often cited, is the recommended classification for external surfaces of buildings over 18m from the ground, or within 1m of the site boundary at any height.  Class 0 is not a classification identified in any BS test.  Class 0 is achieved if a material or the surface of a composite product is either:

  1. composed throughout of materials of ‘limited combustibility’, when tested to BS 476-11 or classified as Class A2-s3, d2 in accordance with EN 13501-1;  or
  2. a Class 1 material which has a fire propagation index (I) of not more than 12 and sub-index (i1) of not more than 6 when tested to BS 476-6:  I is overall performance and i1 is performance after 3 minutes.

(To restrict the use of materials which ignite easily, which have a high rate of heat release and/ or which reduce the time to flashover, maximum acceptable ‘fire propagation’ indices are specified.)

Neither Class 1 nor Class 0 materials are necessarily fire resistant to BS 476-22 or non-combustible to BS 476-4 (or Class A1 to EN 13501-1).

 

Fires in composite panels

During the 1990s there were at least 30 fires in the UK involving composite panels, [5] both internal and external.  External fires were a minority and arson was the principal cause. [6]

Composite panels had come under increasing scrutiny in the UK since the late 1980s.  There were some well-publicised fire disasters, particularly the 1993 fire at Sun Valley Poultry, Herefordshire, in which two firefighters died.  The large factory had ceilings of composite panels with cores of EPS and PUR, and walls of composite panels with EPS, PUR and Rockwool cores.  Some of the PUR-cored panels had fire-resistant board linings.  However, the primary cause of the devastation was considered to be the EPS-insulated steel ceiling panels, which were secured in place with polypropylene fixings, and which collapsed on the firefighters.  The fatal fire was also one of the most expensive ever fires in the UK:  total losses amounted to £70 million.

The concern was that polystyrene-cored composite panels had become widely used for internal partitioning in within the food industry, particularly cold storage, including applications to which they were not appropriate, like cooking operations.  External panels were predominantly polyurethane-cored.

 

Fires in external cladding

At the same time as concern was developing regarding composite panels, another hazard emerged in connection with external rainscreen cladding:

 

Knowsley Heights fire 5 April 1991

An apartment block in Knowsley Heights, Liverpool, was the subject of an overcladding system in 1989-90.  The scheme comprised overcladding panels fixed to vertical sheeting rails, all of which extended to ground floor level. [7]

“A fire was started deliberately in the rubbish compound outside the 11-storey apartment block.  The fire spread rapidly through a 90 mm gap between the building’s rubberised, paint-covered concrete outer wall and a recently installed rain screen cladding (with limited combustibility).  The fire spread all the way to the highest floor and seriously damaged the outer walls and windows of all the upper floors. …”  [8]

The remedial works involved the introduction of horizontal cavity barriers at each floor level.

 

Garnock Court fire 11 June 1999

There was a fatal fire in Garnock Court, a 14-storey residential housing block in Scotland in 1999.

“ Windows at the corners of a 13storey apartment tower in Irvine, Scotland, had been letting in cold and/or moisture.  In order to eliminate these problems and also to improve visual appearance, new window frames of unplasticized polyvinyl chloride (uPVC) were fixed.  The exterior wall around the window was covered with glass reinforced polyester plastic sheet.  This gave a picture frame effect around the window.  The glass reinforced polyester sheet was also extended below the window.  [9]

On 11 June 1999, a fire started in a flat on the 5th floor.

“ … Within minutes, it burst through the window of the flat.  Seconds later, onlookers reported that a vertical ribbon of cladding on one corner of the block was ablaze.

Ten minutes after that, the flames had reached the 12th floor.  As the fire took hold on the outside of the building, it began to break into the flats above.  By the time the fire brigade arrived, the nine upper floors of the building were engulfed in flames.  A wheelchair-bound pensioner died in the blaze.

The cladding on the outside of the building was suspected of contributing to the fire’s severity, and concerns were raised that housing blocks around the country could be at risk.

… At Garnock Court, the “ribbon of cladding” that transmitted the fire was a strip of floor-to-ceiling PVCu window unit, which was divided into a glazed upper half and a grp lower half.”  [10]

 

4. Fire History in the Gulf

Development of Composite Panels

In the Gulf, although the climate is very different from the UK, composite panels became widely used for the same reasons as in the UK:  as a means of providing a cheap, lightweight, weathertight, insulated building envelope, rapidly erected over the interior structure.  However, the developments within the UK and USA to restrict the use of combustible materials as composite panel cores were not universally followed elsewhere around the world.  In terms of fire safety, the manufacture of the composite panels in many countries was at the beginning of the learning curve, composed of combustible thermoplastic cores.

 

Exterior Cladding Fires in the UAE

Saif Belhasa Building, Dubai

On 6 October 2012 a fire started on the 4th floor of this 13-storey apartment building and spread rapidly to roof level.  The building was clad with metal composite panels consisting of aluminium facing with a polyethylene core.  Nine flats were destroyed and there were two injuries.  A considerable quantity of burning debris fell to the street, damaging five vehicles.  Charred aluminium cladding panels were piled on the ground. [11]

 

Tamweel Tower, Dubai

The 35-storey, 160m high Tamweel Tower apartment and office building in Dubai was completed in 2009.  On 18 November 2012, a fire ignited which burned two separate broad vertical bands of exterior cladding from ground to roof level.  Early opinion included a high-level source, [12] but the Dubai Police forensic department concluded that a discarded cigarette from a balcony had ignited construction rubbish at the base of the tower. [13]

The cladding was aluminium-faced, with a polyethylene core, according to one report. [14]

Witness reports were contradictory as to direction of fire spread, with downward spread from the fall of burning cladding materials reported:

“ The fire then spread down the exterior of the building.  Based on photos and video it appears that the downward fire spread was at least partially due to molten flaming debris from the cladding falling onto lower level balconies and igniting the façade at lower levels.” [15]

This description is consistent with melting of thermoplastic core material, such as polyethylene (LDPE).

Two years later, remedial work had not yet begun and there were ever-increasing estimates of repair costs. [16]  Reconstruction was apparently delayed by negotiations over the extent of cladding replacement and whether or not total replacement was covered by the insurance policy. [17]  Civil Defence insisted that cladding on all four sides be replaced, rather than just the fire-damaged section. [18]  Repair works have recently begun, 3 years after the fire. [19]

The Saif Belhasa and Tamweel fires closely followed two major fires involving rapid vertical fire spread in Sharjah:  the Al Baker Tower on 18 January and the Al Tayer Tower on 27 April 2012.  These fires were among the motivators for the 2012 revision of the UAE Civil Defence Fire Code.

 

The Torch, Dubai

On 21 Feb 2015, a fire started on the 51st floor of the of the 86-storey 352m supertall Marina Torch tower, the 9th tallest in Dubai and just 1 km from the Tamweel Tower, thought to have been started by a cigarette or Shisha coal left on a balcony. [20]  “The blaze rose up one side of the building and down the opposite side, after burning material falling from the initial fire set a lower part of the building ablaze.”  [21]

Eyewitness video shows large quantities of burning material falling from a high-level fire starting a secondary fire at a lower level.  Debris was also carried on the wind:  in the morning the surrounding streets were littered with debris. [22]

Photographs taken in November 2015 show two distinct columns of fire damage on two different corners of the building:  one in the top third of the building on the north corner, presumably directly above the ignition point, and another at mid-height on the east corner, presumably the result of burning debris landing on a broad podium deck and igniting a secondary cladding fire.

 

The Address, Dubai

The 63-storey Address, another supertall (302m) building, is the latest skyscraper to be ravaged by an external cladding fire.  A short circuit in external architectural floodlight wiring, mounted on a ledge formed of horizontal cladding panels between the 14th and 15th floors, is said to have started a fire which spread rapidly up the exterior of the building. [23]

Video recordings of the fire show up to 40 storeys of the building burning simultaneously, with hot metal and flaming core materials from disintegrated cladding panels falling and being carried by the wind, not only to the hotel’s periphery, but further to neighbouring streets and buildings, starting fires on adjacent roofs, despite the Civil Defence fire crews hosing down those roofs from aerial platforms.  The following morning there was fire damage visible from top to bottom of the building exterior.  Delaminated aluminium facings lay all around the Address.  Residual fires were still burning in inaccessible places behind cladding panels.  Fortunately all occupants were evacuated alive thanks to the swift actions and determined efforts of the fire and rescue teams.  It needed a hazardous room-by-room search by police and fire crews before a sleeping guest and a photographer trapped in window-cleaning cables were rescued.

There was at least one sleeping survivor of The Torch fire also.  External fires may not trigger the building’s fire detection / alarm or extinguishing systems.  There has been speculation about possible late alarm (and sprinkler) activation in the Tamweel, Torch and Address fires, but the likely reason is that smoke did not reach the smoke detectors, and heat did not reach the sprinkler heads, until the external fires had become sufficiently developed to break into the interior of the buildings.  When the wind is blowing away from the building, as it was on 31 December 2015, this may initially protect the interior while the fire develops in and behind the cladding.

The cladding on The Address is described by Alumco, the supplier / installer as: [24]

“ Aluminium plastic composite panel is compounded with top and bottom layers of aluminium sheet, Anti-toxic polyethylene core material.

Standard:  According to ASTM, EN or BS Standards as per Client Requirement.”

Polyethylene is a thermoplastic material, which (like EPS) melts and drips as it burns, spreading the fire downwards as well as upwards.  Fire retardant additives can improve fire performance.  Polyethylene has no early history as a composite panel core in the UK.  Early UK composite panel experience was with much thicker (typically 50 – 100mm) foamed plastic cores, but there are now similar thin aluminium / polyethylene (LDPE) core rainscreen panels available in the UK.  Class 1 to BS 476-7, Building Regulations Class 0 and EN 13501-1 Class B can be achieved.

The Alumco panel aluminium facing thickness ranges from 0.15mm – 0.5mm and the standard size is 1220mm x 2440mm x 3 or 4mm thick, so the polyethylene core is only 2 or 3mm thick.  The thin panel provides little insulation in comparison with a thick polymeric foam panel, so it is possible that insulation of some sort was installed within the Alumco panel:  insulation could also be part of the mechanism of fire spread.

Alumco provided 35,000m2 of composite panels for The Address. [25]  Although the composite panels are branded Alubond U.S.A., the panels are said to be of UAE origin, manufactured in a plant established in Sharjah in 2000, with an annual capacity of 7 or 8 million square metres. [26]

Alumco’s website also states:

“ Excellent Fireproof Property

It’s core layer is manufactured with Anti-toxic polyethylene core materials, having the combustion resistance property.  Two surface layers are made of aluminium, which is difficult to be burnt.  Therefore, this is a kind of safe fireproofing materials, which complies with the fireproof demand in building code.”

As the construction of the Address began in 2005 and finished in 2008, there was no obligation for the aluminium composite panels to comply with the UAE Fire and Life Safety Code of Practice (2011), or Annexure A.1.21.Rev 2 regarding fire performance of exterior materials, published in 2012.

Investigations by Dubai’s The National into the testing of the aluminium composite panels suggest that that the American-manufactured Alubond predecessor panel was tested in 2007, not in the suitable NFPA 285 Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components, cited in the 2012 Annexure_A.1.21.Rev 2 to the Civil Defence Code, but in an inappropriate and incomplete test to ASTM (American Society for Testing and Materials) E-119 Standard Test Methods for Fire Tests of Building Construction and Materials, in combination with gypsum board which provided the fire resistance. [27]

 

5. Fire History in China

2015 was a global milestone for 200m high buildings (1000 total overall) and for “supertall” 300m skyscrapers (100 total).  China was pre-eminent in 2015 with 58% of completions, bringing its skyscraper stock up to approximately 40% of the global total. [28]  China has suffered fatal fire incidents involving combustible cladding and insulation.  Two savage fires which engulfed whole buildings demonstrate the potential dangers of combustible cladding and external insulation.

 

Television Cultural Centre, Beijing

Construction was started in 2004 and was expected to be completed in May 2009.  The Beijing Mandarin Oriental hotel was to be the main tenant.  On 9 February 2009, stray fireworks from Chinese New Year Celebrations landed on the roof of the building, 31 storeys up, starting a fire which spread rapidly down to the lower floors, causing the death of a firefighter from toxic smoke inhalation and seven injuries.  The whole 159m high building, topped out but still under construction, was ablaze at the height of the fire.  Hard facts are difficult to find after a news curfew, but insulating foam panels [29] and polystyrene insulation [30] have been implicated.

 

Apartment Building, Shanghai

On 15 November 2010 this 28-storey apartment building, which was under renovation, was consumed by fire.  The 85m high building was fully scaffolded for the installation of energy-saving insulation when the fire occurred. [31]  Sparks from welding operations ignited construction materials and the nylon safety mesh on the outside of the building.  Fire then spread rapidly along the scaffolding and through the interior of the block. [32]  58 people lost their lives and 70 were hospitalised, including 17 who were seriously injured.  Firefighters rescued more than 100 residents and others climbed down the scaffolding.

The fire was believed to have spread on polyurethane insulation to external walls. [33]  “The fire may have been caused by the accidental ignition of polyurethane foam insulation, commonly used in China without the addition of flame retardants.” [34]

 

6. Building Regulations in the UK

In the UK, buildings must be designed and constructed in compliance with the Building Regulations, which are drafted as succinct “functional requirements”.  The requirements of Building Regulations Part B Fire Safety are intended to secure reasonable standards of health and safety for persons in and about buildings.

Building Regulations Requirement B4 (1), which has particular relevance to external cladding systems, states:

” The external walls of the building shall 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.”

Under UK Building Regulations, external walls require fire resistance, although a proportion of openings are permitted.  The fire resistance is generally required to resist an internal fire, but fire resistance from both sides is necessary if within 1m of the site boundary.  The fire resistance does not have to be provided by the external cladding.  External cladding systems are not required to be non-combustible.

In addition, ‘Approved Documents’ are published by the Government for the purpose of providing practical guidance on compliance with the Building Regulations for some of the more common building situations.  The Approved Documents offer alternative means of compliance with the Building Regulations, refer to other published guidance, and permit the designer flexibility to introduce other designs, provided that they meet the functional requirements of the Building Regulations.  There are no provisions for property protection, but Approved Document B Fire Safety advises early consultation with all stakeholders, particularly insurers, who will often require additional fire safety measures before accepting the insurance risk.  The UK insurance industry has produced a number of publications intended to prevent large losses caused by fires.

 

Revisions to Building Regulations and Advisory Documents

As a result of the fire at Knowsley Heights, Approved Document B Fire Safety (ADB) 1992 was changed so that fire performance ‘Class 0′ applied to the inside (cavity) face as well as the outside of rainscreen cladding systems on ‘tall’ (>20m) buildings:

“ 12.6  In the case of the outer cladding of a wall of ’rainscreen’ construction (with a drained and ventilated cavity) the surface of the outer cladding which faces the cavity should also meet the provisions of Diagram 36.”  (i.e. Class 0 rainscreen cladding recommended above 20m height and/or within 1m of site boundary)  (ADB 1992)

There has also been advice regarding combustibility of insulation materials in cladding in ADB ever since 1992:

“ 12.7  The external envelope of a building should not provide a medium for fire spread if it is likely to be a risk to health or safety.  The use of combustible materials for cladding framework, or of combustible thermal insulation as an overcladding or in ventilated cavities, may present such a risk in tall buildings, even though the provisions for external surfaces … may have been satisfied.

In a building with a storey at more than 20m above ground level, insulation material used in the external wall construction should be of limited combustibility …”  (ADB 1992)

ADB 1992 also recommended that the voids within rainscreen cladding be closed by cavity barriers.  The definition of a cavity barrier in 1992 was “ A construction provided to close a concealed space against penetration of smoke or flame, or provided to restrict the movement of smoke or flame within such a space.”   UK guidance makes a distinction between a cavity barrier and a fire stop, which is defined as “ A seal provided to close an imperfection of fit or design tolerance between elements or components, to restrict the passage of fire and smoke.”

ADB 1992, Table 13 Provision of cavity barriers, recommended that for flats, other residential (including hotels) and institutional buildings, i.e. places where people sleep, cavity barriers were to be provided within the void behind the external face of rainscreen cladding at every floor level, and on the line of compartment walls abutting the external wall, of buildings which have a floor more than 20m above ground level. (ADB 1992)  In the complete re-drafting of the 1985 edition of ADB, the earlier advice to close the perimeter of cavities, including around door and window openings, was omitted in 1992.  The recommendation was re-introduced in ADB 2000, for all building types.

Building Regulation requirements are not retrospective, so there was a legacy of buildings that did not comply with the new guidance.

The Knowsley Heights fire also motivated research at the Building Research Establishment (BRE), carried out in 1994.  BRE developed a large-scale fire test method, known as ‘A test for assessing the fire performance of external cladding systems’, submitted to the government in 1996.

Subsequently, as a response to the Sun Valley fire, Appendix F: Fire behaviour of insulating core panels used for internal structures, concerning composite panels, was included in the 2000 edition of ADB, largely as a result of pressure from the fire service.  Although subsequently revised, the advice was and still is directed at internal structures, but explains the fire behaviour of composite core materials and fixing systems which is common to external cladding also: [35]

“ 2.  The degradation of polymeric materials can be expected when exposed to radiated / conducted heat from a fire, with the resulting production of large quantities of smoke.

It is recognised that the potential for problems in fires involving mineral fibre cores is generally less than those for polymeric core materials.

In addition, irrespective of the type of core material, the panel, when exposed to the high temperatures of a developed fire, will tend to delaminate between the facing and core material, due to a combination of expansion of the membrane  [i.e. metal facing] and softening of the bond line.

Therefore once it is involved, either directly or indirectly in a fire, the panel will have lost most of its structural integrity.  The stability of the system will then depend on the residual structural strength of the non-exposed facing, the interlocking joint between panels and the fixing system.

Most jointing or fixing systems for these systems have an extremely limited structural integrity performance in developed fire conditions.  If the fire starts to heat up the support fixings or structure to which they are attached, then there is a real chance of total collapse of the panel system.

The insulating nature of these panels, together with their sealed joints, means that fire can spread behind the panels, hidden from the occupants of occupied rooms/spaces.  This can prove to be a particular problem to firefighters as, due to the insulating properties of the cores, it may not be possible to track the spread of fire, even using infra-red detection equipment.  This difficulty, together with that of controlling the fire spread within and behind the panels, is likely to have a detrimental effect on the performance of the fixing systems, potentially leading to their complete and unexpected collapse, together with any associated equipment.

Firefighting

3. When compared with other types of construction techniques, these panel systems therefore provide a unique combination of problems for firefighters, including:

  • hidden fire spread within the panels;
  • production of large quantities of black toxic smoke; and
  • rapid fire spread leading to flashover.

These three characteristics are common to both polyurethane and polystyrene cored panels, although the rate of fire spread in polyurethane cores is significantly less than that of polystyrene cores, especially when any external heat source is removed.

In addition, irrespective of the type of panel core, all systems are susceptible to:

  • delamination of the steel facing;
  • collapse of the system; and
  • hidden fire spread behind the system.”  [36]

Following the Garnock Court fire, a parliamentary inquiry was undertaken to investigate the potential risk of fire spread in buildings by way of external cladding systems.  The report was published early in 2000. [37]

Witnesses to the inquiry (including the Fire Brigades Union, Loss Prevention Council [technical advisers to the insurance industry], manufacturers of external cladding systems and independent fire safety consultants) suggested that the guidance given in Approved Document B might not be adequate for the purposes of ensuring the safety of external cladding systems in a fire. [38]

The committee concluded:

“18.  The evidence we have received during this inquiry does not suggest that the majority of the external cladding systems currently in use in the UK poses a serious threat to life or property in the event of fire. …

19.  Notwithstanding what we have said in paragraph 18 above, we do not believe that it should take a serious fire in which many people are killed before all reasonable steps are taken towards minimising the risks.  The evidence we have received strongly suggests that the small-scale tests which are currently used to determine the fire safety of external cladding systems are not fully effective in evaluating their performance in a ‘live’ fire situation.  As a more appropriate test for external cladding systems now exists, we see no reason why it should not be used.

20.  We believe that all external cladding systems should be required either to be entirely non-combustible, or to be proven through full-scale testing not to pose an unacceptable level of risk in terms of fire spread.  We therefore recommend that compliance with the standards set in the ‘Test for assessing the fire performance of external cladding systems’, which has been submitted to the British Standards Institution for adoption as a British Standard, be substituted in Approved Document B for previous requirements relating to the fire safety of external cladding systems.

The BRE full-scale fire tests were developed to become:

BS 8414-1: 2002 – Fire performance of external cladding systems.

Test method for non-loadbearing external cladding systems applied to the face of a building.

BS 8414-2: 2005 – Fire performance of external cladding systems.

Test method for non-loadbearing external cladding systems fixed to and supported by a structural steel frame.

The test applies to whole cladding systems with all components, which may include fire barriers of non-combustible material to close any cavity and may also form a continuous band through the insulation, which in practice would be installed at each floor level.  The test method simulates a fully developed fire in a room abutting the external face of a building and venting through a window aperture.  If fire spread away from the initial fire source occurs, the rate of progress of fire spread or tendency for collapse should not unduly hinder intervention by the emergency services. [39]

The specimens of cladding systems tested must have a minimum extent of 1.2m x 2.4m, in an internal corner, and 6m high above the top of the combustion chamber opening: [40]  a much more realistic test of the fire performance of a cladding system than the previous small-scale surface spread of flame tests.  The extent of damage caused to the external cladding system is evaluated, specifically the ability of the external cladding system to resist the propagation of the fire 2.5m upwards for at least 15 minutes. [41]  Any falling debris and fire penetration from the external to internal face should also be assessed. [42]

BRE report (BR 135) Fire performance of external thermal insulation for walls of multi-storey buildings was revised in 2003 to incorporate the knowledge gained.  BR 135 was revised again in 2013 to address new technologies in cladding and external wall systems and the publication of BS 8414-2.

 

The View of the Court

Following a fire at Sahib Foods production factory, Southall, in January 1998 with a loss of £17million, and despite the court finding considerable negligence by the occupant, there was a civil court judgment against the architect for specifying internal EPS-cored composite panels, for the total loss, physical and consequential trading loss, beyond the room of origin.  (On appeal the award was reduced by two-thirds, because of the contributory negligence.)

There was no loss of life or personal injury in the fire.  The building was provided with adequate means of escape.  The premises had a Fire Certificate.  There was no question of a breach of the Building Regulations or any other statutory requirement.

However, the Judge “…was not the slightest impressed by the submission that since the defendants had complied with their statutory requirements and as a result no one was killed or injured they had fully performed their duties.  Nor was I impressed by repeated submissions that warnings about this sort of fire were ‘insurance led’.  That submission seems to me to be close to the frequent thief’s submission that the only people to suffer from his activities are insurers.”  [43]

UK Building Regulations generally only require that reasonable standards of health and safety are secured for persons in or around buildings.  The Sahib -v- PKS judgment made it clear that protection of property from fire is also an obligation for the architect / specifier, in the view of the High Court in England & Wales.  The view that the building is sacrificial in fire incidents, provided there is no threat to persons, became no longer sustainable.

 

Insurers

Insurers had huge exposure to claims involved with the use of composite panels, because there was risk of total loss in the event of these panels becoming involved even in any small fire.

Insurers’ attitudes to composite panels began to change in the mid-1990s.  Building cover became more difficult to obtain and premiums rose.  The insurance industry began to take the lead in the protection of property from fire, in the absence of a lead from designers or legislators.  The desired outcome was improved building standards at modest additional cost, leading to fewer and less-serious fire losses for businesses and fewer construction disputes, with a consequential slowing of the increases in property (and professional indemnity) insurance premiums.

Insurers devised their own standards, Loss Prevention Standards (LPS) for both internal and external composite panels, in excess of Building Regulations requirements.  LPS 1181 set the required performance for sandwich panels that will not make a significant contribution to fire growth.  LPS 1208 is a standard for fire-resistant panels, applicable to internal compartment walls, but also to external walls close to the property boundary and external walls at risk from arson attack.

 

Firefighters

From the time of the Sun Valley fire in 1993, where two firefighters died, fire crews became less likely to enter buildings containing composite panels.  Previously, the fire service was naturally reluctant to abandon any building to destruction, but then became less prepared to risk the lives of crews to protect unoccupied property.  If a fire had developed to life-threatening proportions, fire fighters would withdraw and tackle the blaze ‘defensively’, i.e. from outside of the building only.  The brigade’s primary concern was often to prevent the fire spreading to neighbouring buildings.

 

The Regulatory Reform (Fire Safety) Order 2005

In the UK since 2006, under the Regulatory Reform (Fire Safety) Order 2005 (“FSO”), building owners, employers and occupiers have been legally obliged to evaluate fire risk in all buildings other than private dwelling houses.  The FSO is applicable to apartment blocks with common entries, staircases and landings.

The main duty holder in relation to the premises is the “Responsible Person”, defined in Article 3 of the FSO:  the employer, or occupier, or owner, who has duties imposed in relation to fire safety on the premises.  There is a general duty to ensure, so far as reasonably practicable, the safety of employees;  a general duty, in relation to non-employees to take such fire precautions as may reasonably be required in the circumstances to ensure that premises are safe;  and a duty to carry out fire risk assessments.  The duties are ongoing:  an obligation to regularly review, maintain and manage the fire safety strategy of the building.

Article 4 of the FSO requires fire precautions to be taken including measures to reduce the risk of fire on the premises and the risk of the spread of fire on the premises.

Article 9 of the FSO requires that the Risk Assessment must take account of all the risks to which building occupants, and persons in the immediate vicinity of the premises, may be exposed.

The Risk Assessment must be reviewed on a regular basis to keep it up to date and particularly if:

  • there is reason to suspect that it is not longer valid; or
  • there has been a significant change to the building, or its operation.

Article 18 of the FSO requires the Responsible Person to appoint one or more competent persons to assist him in undertaking the fire prevention and fire protection measures, unless he or an employee has sufficient training and experience or knowledge.

 

7. Fire Safety Regulation in the UAE

Fire safety regulation in Dubai is described in the UAE Fire and Life Safety Code of Practice (2011), also known as the Civil Defence Fire Code, which is effective in all the Emirates.  Its intention is to minimise the risk of fire and to ensure the safety of life and property, unlike UK Building Regulations, which are almost exclusively concerned with life safety, rather than property protection.

The code is substantially based on NFPA standards (USA), adapted for local purposes.  However, elements of the Gulf Cooperation Council (GCC) Code of Practice, the International Code Council (also USA), British Standards, European Standards and the Singapore Fire Code are also incorporated.  One commentator has said “… the context and enforcement mechanisms in which those codes developed are often missing or lacking in comprehensive application.”  [in Gulf building regulation] [44]

In the Civil Defence Fire Code there are 22 classifications of buildings:  six definitions based on height, 14 based on function and two on multi-purpose use.  The provisions of the code apply to “Lowrise, Midrise and Highrise buildings”, defined as:

Lowrise             <15m    above level of fire service access;

Midrise              15-23m above level of fire service access;

Highrise             >23m    above level of fire service access.

 

Revisions to UAE Fire Code regarding Exterior Cladding

Following the major fires in Sharjah in early 2012, an appendix was introduced to the Civil Defence Fire Code specifically regulating fire stopping, curtain walling, exterior cladding, exterior insulation and finish systems (EIFS) and roofing of new buildings.  Annexure A.1.21. Revision 2 came into effect in September 2012 (for new approvals) and April 2013 (for installation of cladding), superseding the earlier requirements of the Civil Defence Fire Code regarding the external building envelope.  The Annexure is clearly intended to exclude the insulation and cladding materials most prone to external fire spread.

Annexure A.1.21. Rev 2 specifies mandatory requirements, rather than ‘informative’ advice as in British Standards, or UK Building Regulations ‘Approved Documents’.

Annexure A.1.21. Rev 2 prescribes the required fire performance of exterior materials whilst keeping options open for procurement sources.  It cites US, German, British and EU classifications and testing regimes, with some variation of options between them:

Paragraphs 4.2.4 (Exterior cladding for Highrise, Midrise and <3m from a boundary) and 4.3.4 (Exterior cladding for Lowrise and >3m from a boundary), when referring to the fire performance of cladding panel cores, allows both British Class 0 tested to BS 476 Parts 6 and 7 and Euroclass A1 to EN 13501-1, which is effectively non-combustible and a significantly superior fire performance standard to British Class 0.  Class 0 limits the rates of surface spread of flame and of fire propagation, but can be achieved by materials which are combustible in a fully developed fire.

Similarly, paragraph 4.5.4 regarding exterior insulation and finish systems (EIFS) and external thermal insulation composite systems (ETICS) allows both British Class 1 as per BS 476 Part 7 and Euroclass B, which is a more demanding standard.

Sub-paragraph 4.5.4.1 refers to “Non-flammable polystyrene” which is not attainable:  polystyrene may have a limited rate of flame spread, but all organic materials are   combustible.

Sub-paragraph 4.5.6.2.a.ii refers to Euroclass B1, which does not exist.

Consequently the required fire safety standards in Annexure A.1.21. Rev 2 are not uniform.  A table of equivalence of the various standards cited would be a helpful addition, and it would allow for a reference to be added to the UK “materials of limited combustibility” to BS 476 Part 11.

Section 3 deals with Fire Stopping Systems.  Annexure A.1.21. Rev 2 does not include the UK concept of “cavity barriers”, so the requirements for cavity barriers and for fire stopping are effectively the same.  The standard required for fire stopping is equivalent to the “barrier” in which, or adjacent to which, it is located:  “barrier” meaning the compartment wall or floor in UK terms.  The firestop system must have a fire resistance of at least 1 hour in integrity, and 15 minutes in insulation, determined by testing to established standards.  The recommendations of UK Approved Document B are similar for fire stopping, but advise only 30 minutes integrity for cavity barriers.

The fire stopping requirements include penetrations of compartment floors and walls and the junctions of compartment floors and curtain walling.  There does not appear to be a general requirement to provide cavity barriers / fire stops to seal and sub-divide concealed voids to inhibit the unseen spread of fire, as in the UK Building Regulations.  There does not appear to be a specific requirement to close cavities around door and window openings.

Section 4 deals with Exterior Wall Cladding Systems.  Paragraph 4.1 makes it clear that the system has to include insulation, silicone or fillers between panel joints and fire stops, tested as an assembly.  Paragraph 4.2 concerns cladding on midrise (15-23m), highrise, mall, assembly, hospital and educational buildings within 3m of the site boundary.  The requirements apply to the entire cladding of the building, whatever the proportion of cladding in the building envelope.

Sub-paragraph 4.2.2 prohibits foamed plastic cores absolutely.

Sub-paragraph 4.2.4 however permits plastic (density > 320 Kg/m3), rather than foamed plastic (density < 320 Kg/m3) cores, provided that they meet of any one of 8 listed US, UK, German or European standards, which are not all equivalent:  see above.

The corresponding guidance in UK Approved Document B, paragraph 12.7, is that in a building with a storey 18m or more above ground level any insulation product, filler material (not including gaskets, sealants and similar) etc. used in the external wall construction should be of limited combustibility.  “Limited combustibility” is a standard superior to Class 0, approximately the equivalent of EN 13501-1 Class A2, but inferior to UK “non-combustible” and Class A1 to EN 13501-1.

Sub-paragraph 4.2.5 has stringent requirements for the cladding panels.  The European Class A1 to EN 13501-1 is acceptable, but the UK equivalent “non-combustible material” is not mentioned, although BS 476 part 4: 1970 Non-Combustibility test for materials is listed as a test for non-combustible material in paragraph 2.27.

Sub-paragraph 4.2.6 requires the whole cladding system assembly, with intended cladding panel, core, insulation, joints, seams, fasteners and wall arrangement to be tested in large scale tests to US Factory Mutual or BS 8414 standards.  BS 8414 testing would tend to compensate for the absence of a prescriptive requirement for cavity barriers.

For an external cladding system the UAE Code is much more demanding than the recommendations of the UK Approved Document B which accept BS 8414 testing, but also the inferior Class 0 standard, for buildings over 18m high and within one metre of the boundary.  In the UK, buildings over 1m from the site boundary may have EN 13501-1 Class C cladding below 18m above ground, and timber cladding is acceptable.  UK experience would suggest that the incidence of external envelope fires in the UAE, in buildings constructed from 2013 onwards, should be hugely reduced or eliminated by Annexure A.1.21. Rev 2, provided that the Code is followed in both the design and construction.

 

8. The Conundrum of Existing Buildings with higher risk cladding

The remaining problem is the legacy of buildings with combustible cladding constructed before standards were changed.  The problem is greatest where the 21st century development boom has been most vigorous, particularly in China and the Gulf countries.

Regarding tall buildings, since the World Trade Center was completed in 1979, Dubai achieved such extraordinary growth that 134 skyscrapers exceeded its 149m height prior to the change of standards in 2013, [45] and there are countless other tall buildings.  A proportion of these have aluminium panels with a thermoplastic core:  the proportion estimated as high as 70% in the press, but estimated as only 10 – 20% by the Director of the preventive safety department for Dubai Civil Defence. [46]  Even so, there is a huge number of occupied buildings at risk.  Almost certainly there will also be combustible insulation present, open voids behind cladding and absence of fire stopping at floor levels, compounding the risk.

Annexure A.1.21 to the Civil Defence Fire Code states:

“ 1.5.  For the buildings that are existing and have Cladding/Curtainwall systems on the building envelope, it is highly recommended to the Building Owner to have the perimeter wall evaluated through Civil Defence approved House of Expertise and resolve non-compliances through alternative solutions.”

This sub-section appears to be informative/advisory, unlike all the rest of the Annexure which is mandatory (“shall be”).  At present, there is no equivalent legislation to the UK Regulatory Reform (Fire Safety) Order 2005, but Dubai’s The National news service has reported that a proposed update to the UAE Fire Code anticipated in March 2016 will include a new section about liabilities. [47]  Matters to be included would be the building’s operations, the building’s maintenance and systems, tenant responsibilities, and the requirement for a consultant appointed by the Building Owner to monitor the building process.  The extent to which this awaited revision to the Fire Code will, or will not, apply retrospectively to existing buildings is not yet clear.

Can anything be done about the worldwide legacy of buildings with combustible cored composite panels?  Unless something radical is done, such as national retro-fitting subsidy schemes, it seems inevitable that there will be further fires involving aluminium-faced polyethylene core panels.  Nightmare scenarios include multiple-fatality building-engulfing fires as in China, or given the proximity of towers in some districts, the ignition of neighbouring buildings’ cladding from an external cladding fire, or disintegrated burning panels igniting the roofs of lower buildings adjacent.

It is difficult to envisage owners voluntarily stripping off entire existing aluminium composite panel facades and replacing them with Fire Code-compliant cladding panels, as the cost would be prohibitive.  Partial replacement with barrier bands of fire resistant panels has been suggested to stop fires spreading, [48] but given the flame heights at the Tamweel, Torch and The Address, such barrier bands would have to be substantially large.  The works necessary to provide these barriers would involve much of the scaffolding and associated costs of full replacement.

It seems inevitable that insurers will differentiate between buildings with and without combustible aluminium composite panels and will charge higher premiums for higher risks.  One or two more fires, or a fatal fire, could lead to insurance cover being refused if the risk is considered excessive.  Insurance issues, bad publicity and loss of property value might then make retro-fitting external cladding a viable option in commercial, as well as fire safety terms.

…………………………………………………………………..

[1]  Fire Safety of Sandwich Panels, FRDG 1997.

[2] External Fire Spread – The testing of building cladding systems, Sarah Colwell, BRE

[3] BR 135 Fire performance of external thermal insulation for walls of multistorey buildings. 3rd edition BRE (2013)

[4] General Insurance Research Report No. 6, ABI 2000 or 2001.

[5]  Firefighting Options for Fires involving Composite Panels, FRDG 1999, Table 1.

[6]  Fire performance of sandwich panel systems, Association of British Insurers (ABI) 2003, 4 External Claddings, Table 1.

[7]  Potential risk of fire spread in buildings via external cladding systems  House of Commons Environment, Transport and Regional Affairs Committee, 14 December 1999  (HC109), Appendix 6. Knowsley Metropolitan Borough (ROF 02).

[8]  Burning issues,Architects Journal 31 May 2001.

[9]  Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, Fire Protection Research Foundation (NFPA) 2014.

[10] Cladding: the new rules, Building, 2000 issue 06.

[11] Fire in Tecom building leaves seven families homeless, Gulf News 6 October 2012.

[12] Fire breaks out at Tamweel Tower in Jumeirah Lake Towers, Gulf News 18 November 2012.

[13] Tamweel Tower fire started by cigarette butt, say Dubai Police, The National 4 December 2012.

[14] Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, Fire Protection Research Foundation 2014.

[15] Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, Fire Protection Research Foundation 2014.

[16] Two Years Later, Cost to Repair Fire-Damaged Dubai Tower Soars to $21M,  Council on Tall Buildings and Urban Habitat Global News 17 November 2014

[17] Insurance company agrees to repair fire damaged Tamweel Tower in Dubai, The National 14 January 2013.

[18] Cladding used on The Address Downtown ‘did not meet fire safety standards’, The National 12 January 2016.

[19] ArabianBusiness.com 17 December 2015

[20] Dubai Inferno: 5 of History’s Worst Skyscraper Fires, IFSEC Global 24 February 2015.

[21] Dubai Marina Torch Tower fire: Londoner tells of how he slept through a towering inferno, The Telegraph, 22 Feb 2015.

[22] British flight attendant questioned over Dubai blaze  Mailonline 4 March 2015

[23] Dubai police chief, quoted in 7 Days and The National 20 January 2016.

[24] According to the supplier’s website

[25] According to the supplier’s website

[26] According to the manufacturer’s website

[27] Revealed – how The Address Downtown Dubai hotel fire test was ‘meaningless’, The National 12 January 2016.

[28] Source: Skyscraper Center

[29] China TV Network Apologizes for Fire, New York Times, 10 February 2009.

[30] Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, Fire Protection Research Foundation 2014.

[31] New York Times November 15, 2010.

[32] Guardian 15 November 2010.

[33] Fire Hazards of Exterior Wall Assemblies Containing Combustible Components, Fire Protection Research Foundation 2014.

[34] Dubai Inferno:  5 of History’s Worst Skyscraper Fires, IFSEC Global.com 24 February 2015.

[35] Appendix F: Fire behaviour of the core materials and fixing systems, to Approved Document B (ADB) 2000

[36] Appendix F: Fire behaviour of insulating core panels used for internal structures  to Approved Document B (ADB) 2000/2006

[37] Potential risk of fire spread in buildings via external cladding systems  House of Commons Environment, Transport and Regional Affairs Committee, 14 December 1999  (HC109).

[38] Architects Journal 31 May 2001.

[39] BR 135 (2013) Annex B:  Performance Criteria and Classification for BS 8414-2, B2 Performance Criteria and Classification Method.

[40] BS 8414-2: 2005 Fire performance of external cladding systems, 4. Principle  and 6. Test specimen.  All(you are

[41] BR 135 (2013) Annex B:  Performance Criteria and Classification for BS 8414-2, B2 Performance Criteria and Classification Method, B2.2 External fire spread.

[42] BS 8414-2: 2005 Fire performance of external cladding systems, 4. Principle  and 6. Test specimen.

[43] Sahib -v- PKS Judgment 03/03/03, 43.

[44] Thom Bohlen, Middle East Centre for Sustainable Development, in ‘Towering inferno’ fears for Gulf’s high-rise blocks, BBC News 2 May 2013 

[45] The Skyscraper Center, Council on Tall Buildings and Urban Habitat

[46] Cladding used on The Address Downtown ‘did not meet fire safety standards’, The National 12 January 2016

[47] Updated UAE fire security code will ensure buildings’ safety, The National  13 January 2016.

[48] The Torch blaze reignites concerns over cladding used for Dubai towers, The National  9 March 2015.
…………………………………………………………………..