Insulated core panels
Many buildings have insulated core panels as exterior cladding or for internal structures and partitions. The food industry, in particular, uses insulated core panels because they are easy to clean and facilitate consistent temperature control within the premises. The simple construction of these panels enables alterations and for additional internal partitions to be erected with minimum disruption to business.
They normally consist of a central insulated core, sandwiched between an inner and outer metal skin. There is no air gap. The external surface is then normally coated with a PVC covering to improve weather resistance or the aesthetic appeal of the panel. The central core can be made of various insulating materials, ranging from virtually non-combustible through to highly combustible.
Differing fire hazards associated with common types of insulation, when the panels are subjected to certain temperatures.
Typical examples are;
Mineral rock/modified phenolic will produce surface char and little smoke or gaseous combustion products, at temperatures above 230 degrees C.
Polyisocyanurate (PIR)/Polyurethane (PUR) will char and generate smoke and gaseous combustion products, at temperatures above 430 degrees C PIR and 300 degrees PUR.
Expanded polystyrene (EPS) will melt and will generate smoke and gaseous combustion products, at temperatures above 430 degrees C PIR.
Insulation charring can lead to panel delamination/collapse, and the gaseous combustion products can fill areas with the toxic gases carbon monoxide and styrene. A number of fires in buildings where insulated panels have been used extensively in the fabric of the building have highlighted the particular dangers that may be associated with this form of construction, i.e. where the fabric of the building can contribute to the fire hazards.
In a fire the following may occur;
Early buckling and falling away of the facing materials.
Burning of the combustible insulating material.
Production of large quantities of dense, toxic smoke.
Rapid heat generation.
Early loss of structural strength can result if the system has not been properly designed, and this can lead to the collapse of the wall, partition or ceiling.
There may be cavities in older buildings where the panels are used as an internal envelope, enabling fire to spread unnoticed and possibly unchecked by fire barriers. Once installed it is difficult to identify the core material of a panel and its potential fire hazard.
The following best practice can help you reduce risks associated with insulated products;
Do not install heating appliances, such as ovens, against the panels. Operate a clear distance policy for cooking systems. Control ignition sources that are adjacent to, or penetrating the panels. Control hot working Check for damage to heater tapes used to prevent ice build-up at doors. Do not store highly combustible materials against panels or allow rubbish to collect against panels. Have damaged panels or sealed joints repaired immediately and make sure that jointing compounds or gaskets used around the edges of the panels are in good order. Check where openings have been made for doors, windows, cables and ducts to ensure that these have been effectively sealed and the inner core has not been exposed. Check that there has been no mechanical damage and repair any that has occurred, e.g. caused by mobile equipment such as fork lift trucks. Ensure that any loads, such as storage and equipment, are only supported by panels which have been designed and installed to perform this function. Check that the inner and outer skins are adhering tightly to the core. Ensure that the panels are correctly secured to the structure or are designed to be independently structurally secure. One solution is to ensure the retaining brackets bolt to the panel to a support frame through the outer and inner skins. Ensure large roof cavities are appropriately protected, e.g. escape routes are clear, signed and have limited travel distance, and fire warning systems are audible.
The use of combustible panels in areas of buildings with high life risk, e.g. where large numbers of people are present, should be carefully considered. Your fire risk assessment may need to be revised to ensure that any increased risk resulting from this type of construction is considered.
The potential for fire development involving mineral fibre core is less than that for panels containing polymeric cores. Therefore, in areas where there is considerable life risk, it may be appropriate to consider replacing combustible panels, providing a fire suppression system or installing non-combustible fire breaks within or between the panels at suitable intervals.