Prefab structures such as porta cabins, site offices, labour accommodation large commercial buildings and industrial structures can be built with PUF panels. There is a rigid core sandwiched between two metal sheets on each side of the panel. Insulated sandwich panels made of PUF have joists, studs, insulation, vapor barriers, as well as air barriers. These panels are used as cladding on exterior walls, roofs. A wide range of applications can be accomplished with PUF insulated panels including warehouses, factories, site offices, and many other places.