Installing heat-insulating sandwich panel Sound insulation Water insulation Sandwich panel is a type of building material used for walls. Sandwich panel consists of three main layers: 1. The outer layer is usually made of metal sheets such as galvanized steel. 2. The middle insulating layer, which is the insulating layer that can be made of materials such as polyurethane (PU), rock wool, or polystyrene, and it provides thermal and sound insulation. For inquiries, contact the number (mobile number appears when you click the contact button).