Insulated Sandwich Panels (ISP) have been used for commercial construction in Australia for the past 50 years. Insulated Sandwich Panels (ISP) are made when three separate elements are “sandwiched together” to form one structure, see Diagram 1. The combined properties of the high tensile and compressive strength of the outer steel skins and the high shear strength of the inner core leads to a building material which has a much longer spanning capacity and is lighter in weight than traditional building materials.
The most common cores used in Insulated Sandwich Panel (ISP) construction are Expanded Polystyrene with a flame retardant (EPS-FR), EPS Phenolic HYBRID (Syntactic) (SPS), Polyurethane Foam (PUR), Polyisocyanurate Foam (PIR) and Mineral Wool (MRF) or Rock Fibre.
EPS-FR Expanded Polystyrene Fire Retardant PIR Polyisocyanurate
SPS EPS Phenolic Hybridd (Syntactic) MRF Mineral Fibre
PUR panel has not been extensively manufactured or used in Australia.
EPS-FR is manufactured from styrene monomer, using a polymerisation process which produces translucent spherical beads of polystyrene, about the size of sugar granules. During this process a low boiling point hydrocarbon, usually pentane gas, is added to the material to assist expansion during subsequent processing.The flame retardant predominately used for expanded polystyrene is hexabromocyclododecane (HBCD). HBCD is added during the polymerisation process and is retained within the polymer matrix. New flame retardants are emerging and are currently being trialled.
PIR panels are produced by foam in place as opposed to drop in manufacturing processors.
ADVANTAGES OF INSULATED SANDWICH PANELS
The perceived disadvantage of ISP has been its performance in fires. The most common criticisms of ISP in fire conditions relate to the delaminating of the outer skins exposing the core, the structural ability of the Panels to stay in place and not collapse during a fire and fire spreading within the Panel. There have been improvements over time to ISP and addition of fire retardants, metal fixings, not using plastic fixings, etc. The objective of the Code of Practice ("the CODE") is to bring all of these improvements, and others in further research and testing, together into one system and industry CODE.