Installation of sandwich panel annexes, rooms, corridors according to the required design. Installation of the iron structure and perfecting slopes with iron primer and installation of galvanized gutters for water drainage, and preparing the structure. The last stage is applying sandwich panel sheets for roofs or walls as requested. The walls can be cement board for those who want hidden lighting and control over the color of the panels (i.e., painting). Sandwich panel has multiple thicknesses, starting from 5cm, 7.50cm, and 10cm. It is used for annexes, refrigerators, guard rooms, and roofs for vast areas. The sandwich panel product is the cheapest in price and lightest in weight, and its features include an aesthetic appearance. It insulates sound, rain, and heat.