Garage doors are made of different materials but the most common are wood, steel, aluminium and fibreglass. Each material comes with different options that range from standard to raised panel designs. Some of the terms that you will encounter while buying cheap steel garage doors include single-layer door, double-layer and even triple layer. Single layer doors are made from a single sheet of galvanized steel and will most occasionally be the cheapest. Double-layered doors are made of galvanised steel and backed by another layer of either polyurethane or polystyrene while triple layered doors are made of three layers. However, it is important to note that different materials have different advantages and disadvantages.