Factory assembled insulated sandwich roof panels using PUF/PIR/Mineral-wool are single piece, prefabricated, factory made units consisting of an insulating layer between two sheets of Pre-coated GI/GL sheets of 0.5 – 0.8 mm thickness to produce straight-to-finish panels. The panels are manufactured in accordance with a system patented by Metecno and consists of a profiled external steel facing, an internal flat liner with an insulation core (PUF/PIR/Mineral-Wool). The insulation core provides effective insulation and strong bonding for better structural stability to facilitate higher loading and wider spans. These roof panels can be used for roof, wall and ceiling applications.