The sandwich panels / Insulated panels that are used for construction constuction of cleanrooms come with skin without any ribs on them (Flat surface) to ensure no contamination takes place and an easily washable surface. PUF (Polyurethane Foam), PIR (Poly Isocyanurate), EPS (Expanded Polystyrene), and rock wool are the core insulation materials. The Tongue and Groove panels are manufactured on a continuous manufacturing method in a continuous line or discontinuous batch production. On the continuous line, any length panels can be manufactured subject to transportation. In discontinuous/ batch production, generally, the length is limited to 6 – 9m. These panels are also known as PROGERESSIVE PANELS. There is another type which is known as NON – PROGRESSIVE PANELS. Here the skin is Aluminum, SS or PPGI Peripheral Face is covered.