Sandwich Panel Fire Risks

With June Insurance Policy Renewals in full swing, we are being inundated with requests to conduct insurance surveys on buildings with substantial amounts of Expanded Polystyrene Sandwich Panel (sometimes called Insulated Sandwich Panel). The panels are highly efficient insulators and used in cool rooms, cold store warehouses and food processing buildings. There have been several large fires in recent times and, due to the potentially highly flammable nature of the material and the difficulties in fighting these fires, the losses are usually substantial or total. The findings into the causes usually reveal “abuse” of the panels including mechanical damage, incorrectly made penetrations and stacking of combustible items in close proximity. Download our Sandwich Panel Management Procedure which includes proper procedures for working with or modifying sandwich panel as well as a work permit form. Download Here.

Some Useful Info:

The British Fire Research Station was commissioned to carry out research into the fire safety of large insulated sandwich panels (LISPs) in buildings. See Full Report

At the meeting of the Joint Fire Safety Committee of the CFBAC in autumn 1995, the Fire Brigades Union expressed concern about the use of large insulated sandwich panels (LISPs) following the fire in September 1993 at the Sun Valley Poultry Ltd chicken processing plant in Hereford in which two firefighters lost their lives. FRDG agreed to consider as a matter of urgency what research could be carried out and as a result, the Fire Research Station were commissioned to carry out a short research project for FRDG to determine the extent of the problem and what could be done about it.

The safety of firefighters in buildings containing sandwich panels is the main concern although building occupants may also be at risk. Other factors are the possibility of large property losses and environmental pollution.

There are also concerns from the insurance industry that fires in buildings containing sandwich panels often result in the loss of the building. Consequently the Loss Prevention Council has introduced fire performance criteria for panels. Also, the International Standards Organisation (ISO) is seeking to develop a large scale fire test for sandwich panels.

What Are LISPs?

Sandwich panels take many forms but concern is centred around those with metal skins, and with “fillings” made of one of the following materials:

• expanded polystyrene
• polyurethane
• mineral fibre (also known as mineral wool)

As the filling material may be combustible there is a potential fire safety problem which needs to be considered. The panels are usually between 50mm and 200mm thick.

Conclusions

1. The findings of this study support those from fire statistics, namely that the risks associated with sandwich panels are primarily in fire fighting. While there may be circumstances in which members of the public or workers in a building are put at risk directly from a burning sandwich panel, the evidence here is that, if panels are the item first ignited, development will be fairly slow and contained and that panels will only contribute to an already large and dangerous fire.

2. Different types of sandwich panel burn in different ways. Mineral fibre panels are noncombustible, and developments in the formulations of some types of polymeric cores will limit fire growth. However, there are many existing buildings that contain the older types of product.

3. Large quantities of black smoke are produced, making working difficult for firefighters outside the building as well as inside. In addition, there may be ammonia released from damaged refrigeration plant. There are also a number of pollution risks from fires involving sandwich panels.

4. For fire fighting there are evident risks. The fuel in the panels will contribute to the fire development, and the fire can spread quickly and unseen, both within the panels and within the voids behind and above the panels. As there is no fire resistance requirement for the fixings of these panels this can lead to sudden delamination or collapse of the panels. In addition, the nature of the panels themselves, which are intended to provide a watertight surface for hygiene purposes, makes it extremely difficult for firefighters to get fire fighting water onto such fires.

5. Fire fighters need to be aware of the unusual fire behaviour of sandwich panels, in particular the risk of sudden delamination, which is dangerous in itself, since large thin metal sheets may fall from a considerable height, and can accelerate subsequent fire spread.

6. There is some difficulty in identifying the different types of panel once they are in place and the core hidden. It would be useful to the fire service, and to building owners, if there were some means of identifying the different types of panel once they were in place, for instance by labelling.

7. There is a need for good fire safety management and housekeeping in these buildings. FRS staff have observed blocked exits and stacked combustibles. The nature of fires involving sandwich panels is such that well rehearsed evacuation plans are essential.

Riskex can assist with reviewing your current ISP Risks and Controls

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