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Memoranda submitted to the Environment Sub-Committee of the Environment, Transport and Regional Affairs Select Committee by the Fire Safety Development Group:

Inquiry into the potential risk of fire spread in buildings via external cladding systems

1. Introduction


1.1 On the 11 June 1999 a wheelchair-bound man died in a tower block fire in Irvine. We believe that the fire started in a room on the 5th floor and burst out through the window. Within about ten minutes the fire had spread up seven floors but was contained within the area of the cladding. The fire broke through into the building, possibly by means of the area beneath the windows or the windows themselves, and engulfed the upper nine floors.

1.2 There may have been special circumstances relating to this fire but nevertheless we consider it highlighted a number of aspects of fire safety which need to be addressed. These are:

1.3 Firstly, a distinction between products that conform to the Class 0 standard inherently, or through modification by additives.


1.4 Secondly we seek urgent action from the DETR to regulate the use of plastics and to reduce the threat to life from toxic smoke and burning droplets. We have assumed the Committee will be professionally advised, and have therefore written our evidence accordingly.

1.5 We have been informed that the windows at the corners of the tower block had been letting in cold and or moisture. In order to eliminate these problems and also to improve visual appearance, new window frames of unplastised 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. We do not know if the fire was spread by means of the surface of the plastic sheet or whether the fire spread within a cavity that may have existed between the cladding and the original external wall.

Memoranda

2. Whether a risk is posed by such cladding

2.1 Regulations in Scotland, England and Wales specify that exterior cladding should be Class 0 fire performance. Class 0 is the highest category for surface spread of flame of a material and is defined in the Approved Document B Fire Safety to the Building Regulations (England and Wales 1991). This definition is also used in the British Standard (Scotland) Regulations.

2.2 We believe that there is confusion about the Class 0 standard for two reasons. Class 0 materials refers to the performance of the surface of the material, but applies to the total product i.e. the facing plus any coating, adhesive, paint etc. plus the substrate to which the facing is bonded. Clearly these other elements will affect the performance of the cladding in a fire, and will vary with the nature of the coating, the thickness of the adhesive, the type of substrate etc.
2.3 A material of limited combustibility can achieve a Class 0 rating as defined by the regulations but a Class 0 material is not equivalent to a material of limited combustibility. A material of limited combustibility is generally a material which is totally non-combustible or which contains a small amount of combustible material. Combustible materials, like plastic, wood etc are not materials of limited combustibility but can achieve Class 0 performance by adding fire retardant chemicals or facing the combustible material with a metal foil or sheet. Thus there is a fundamental difference between products that are inherently Class 0 and products modified to enhance their performance. This serves to undermine the integrity of the regulations and therefore reduces fire safety.

2.4 Confusion often occurs because some manufacturers refer to Class 0 products without due consideration for the way the product will be used or treated. The performance of an external cladding sheet which, when tested alone and meets the requirements of Class 0, could easily be downgraded to an inferior level by painting the sheet with the wrong type of paint.



2.5 We believe that both methods can suffer from technical problems, particularly for products used for exterior applications, when the additive may not be durable. With time, the performance will fall to a lower level. If a facing foil or laminate has been used on the plastic material, this could be damaged with time or delaminate due to loss of adhesion between the foil and the substrate. These types of products still remain combustible and will contribute to fire load in the event of fire. Higher levels of smoke will be developed when combustible materials burn than for materials of limited combustibility. Furthermore, in the case of thermoplastics, they could drip in the event of a fire and this will exacerbate fire spread.

2.6 It is well known that fire and smoke can spread unhindered in cavities and for this reason, regulations specify cavities should be divided at certain intervals depending on the nature of the cavity. If the requirements had been followed, we do not think the fire would have spread as described in the newspaper reports but further investigation should show if cavity barriers were lacking.



2.7 The cladding appears to have helped spread the flame over the surface and may also have been consumed by the fire. However, it may not have been considered necessary by the designers/specifiers to use a product with Class 0 performance as the sheet may have been classed as a window frame rather than an external cladding. If the plastic cladding used on the building had a lower spread of flame than required by regulations or insufficient cavity barriers were used, then we consider that this system presented a fire risk.

2.8 We understand that the uPVC window frames made a big contribution to the rapid spread of the fire and its entry into the upper parts of the building. This would help to explain how the fire could burst out of the flat where it started, and then manage to get back into the tower block to destroy the floors above the fifth floor.

2.9 We are concerned about the increasing use of plastic and combustible materials on the face of buildings and consider that their use should be examined in more detail. Building regulations do not pay sufficient consideration to the effect of fires spreading by external means. Smoke and flames issuing from windows can be very severe and easily affect other parts of the same building.



2.10 There is an increase in the use of plastic products and in particular uPVC for renovation work on the exterior of buildings and we consider their use should be examined in more detail. As the work is frequently for small repair and maintenance work, detailed planning permission may not be required and the application is unlikely to be covered by any fire regulations.

2.11 The uPVC window frames in the Irvine fire were stated to have melted. This is a common occurrence with this type of thermoplastic and has occurred in other fires. We have had experience of a plastic soffit lining board melting and molten plastic falling on fire fighters below. The molten material also helped to spread the fire within the building although the product had been used for an exterior application. In this case, the plastic soffit board was destroyed which then enabled the fire to enter the roof space and spread throughout the building. One fatality occurred. A picture showing this fire is included.

2.12 Our understanding is that at present the DETR have no plans to reconsider the relevant regulations. We think this ill-advised. We also believe it is necessary to consider that contribution made to the fire by burning plastic building materials and in particular foam plastic cores of external composite cladding panels.

3. The extent of the use of external cladding systems

3.1 External cladding systems are widely used both in new building and in refurbishment work. We understand the type of plastic cladding used on the property in Irvine is widely used throughout Scotland. However, we believe the fire spread and re-entry to the building was probably a consequence of the PVC window framing and sills. We do not think this type of alteration is widespread but it should be looked into.

4. The adequacy of the regulations pertaining to their use

4.1 We believe the present regulations in England and Wales were revised in 1991 to ensure that cladding systems did not spread fire and present a risk. As a result of the experience with a fire that spread within the cavity behind an external cladding system, the Approved Document B was changed to specify that combustible insulation was precluded from external wall construction in buildings with a storey at over 20m above ground level. The Scottish regulations were amended in 1997, after fears that a fire could spread up a cavity. Since then, every opening has had to have a seal.

4.2 We believe that not only should the external face of the cladding be Class 0, in accordance with the regulations, the Class O standard should also apply to the inner face of the cladding sheet where there is a cavity behind the external sheet.

4.3 We do not consider there is adequate regulation governing the use of plastic products on the exterior of buildings. Responsibility for implementation may be split between Building Control and the Fire Authorities and it is not always clear which authority is responsible for renovation work.

4.4 We also wish to make a distinction in the regulations between integral Class 0 materials and modified products. This should reflect the different fire performance between a non combustible composite cladding and one consisting of a metalBface foam plastic.

5. What action may be necessary to counter any risks posed in existing building and to avoid any risks in new buildings or alterations to existing buildings

5.1 We do not consider there should be a wholesale review of all external cladding systems, as we are sure that the majority will have met regulatory requirements. A more detailed study is, however, needed to examine the fire behaviour of thermoplastic products when used in exterior applications. When plastic window frames could be affected by fire as a result of the design of external cladding systems, some form of fire protection may be necessary to protect the frame. Alternatively, fire barriers should be used to prevent fire ingress into the building.

5.2 Thermoplastic products should not be used in areas where they could melt or be destroyed by fire and thus add to the spread of fire. It may therefore be necessary to replace some of these plastic products with materials of limited combustibility.

5.3 There is also widespread concern amongst many fire fighters about the safety of external cladding systems consisting of metal faced foam plastics. These systems will generally have Class 0 fire performance, but in real fires the foam plastic lining can ignite and burn. This helps to spread the fire via the building fabric and there will be an increase in the generation of smoke and toxic fumes. Collapse is also possible. We believe this subject is still being reviewed by the DETR and consider more stringent controls a priority.
6. Other matters which may arise in the course of questioning

6.1 We have highlighted some problems with burning plastics which this fire has raised. There is at present nothing in Building Regulations to require control of smoke, fumes or burning droplets from building materials. This should be rectified as the increasing use of plastic materials means there will be further instances of burning or molten plastic helping to spread the fire or causing injuries to fire fighters or building occupants. The DETR should act to rectify this, especially as Home Office Statistics consistently demonstrate how more people die in fires after being overcome by smoke than any other cause.

6.2 We consider the use of Class 0 materials should be more stringently controlled for external wall cladding. Products which can only achieve this rating by means of surface treatments, coatings, foil coverings or impregnation treatments should not be allowed.



6.3 Apart from the specific recommendations for improvement we have proposed in our Memoranda, there is an overall broad but important point to make. The Irvine incident once again illustrates the unpredictable and unexpected nature of fire.

6.4 This view was well expressed recently (FSDG Seminar on Fire Issues, House of Commons, February 1999) by Frith Hoehnke, an architect who carried out the extensive revision of Scottish fire safety building regulations which came into force in 1997. Mr Hoehnke then said: "I would never advise a client to cut anything to do with fire to the bone because, when I look at the fire reports of actual fires, the most incredible things have happened. ... So far as fires are concerned it is really the unexpected that defeats us on many occasions. Indeed, it is usually when not just one thing goes wrong but one, two or three things go wrong at the same time that all our defences are breached and disaster strikes".

6.5 We concur with this opinion. It raised the question of whether regulatory decisions about fire safety in buildings should be left as they currently are within the BRAC or (in the case of Scotland) the BSAC remit. Clearly both these bodies call in expert opinions but they do not always reflect a full range of available specialist experience.

 6.6 The Government is currently moving, through the Home Office, to establish a Fire Safety Advisory Board which should bring this wider experience to bear on all fire safety matters. Logically BRAC and BSAC should work more closely with such a body. It might, indeed, finally emerge as a Fire Safety Commission reviewing fire hazards in a continuous and therefore more sensible way. These are, as we said, wider issues but every single incident has its lessons to teach and the Irvine fire should be another providing support for such a broader move.
FIRE SAFETY DEVELOPMENT GROUP
6 July 1999

The Fire Safety Development Group is an alliance of eight leading companies manufacturing structural fire safety products within the UK and Europe.