The best types of sandwich panels depend on the type of insulating material used between the two layers of metal sheets. The outer layers are typically made of materials that protect the insulation and increase the durability of the panels. Roof panels: They usually come with a corrugated design to enhance strength and facilitate rainwater drainage. Wall panels: They are available in flat designs or those with simple ridges, including types with Secret Fix for concealing screws and providing an aesthetic appearance. Cooling room panels: These are thicker (up to 15 cm or 20 cm) to ensure very low temperatures are maintained.