The use of factory pre-fabricated insulated panels has helped to speed up the completion period and simplified the site work involved in the older, masonry shell-with-fieldapplied- insulation type of construction.
The PDF panels are formed by injecting polyol, isocyanide and a foaming gent between two metal sheets in a mould which is then held tight in a heated press for curing. The vertical edges of the panel are moulded in a tongue-and-groove fashion with a locking system, referred to as 'camlock', foamed in place along the panel edges,Maximum length of the panel depends on the length of the mould and press available with the manufacturer and is restricted to 6 metres with Indian companies at this time.
The continuous laminated panel consists of three layers of material bonded together with heat polymerising adhesive, so that they behave as one entity. The outer skins of the panel are normally pre-painted galvanized steel which bears most of the load of the panel. The thicker central core of polystyrene insulation material stabilizes the outer skins and prevents distortion under stress. Any length of panel can be supplied, as long as transport and handling at the site is not a limiting factor. Insulation thickness ranges from 80 to 300 mm of Polystyrene. Panels are joined together by a tight fitting sheet metal 'slip joint' with the insulation edges in tongue and groove fashion.