Windows can be classified into types based on their configuration, or by the material they are made of. Windows are most commonly made of the following materials:
1) Aluminium Windows : Aluminium is a light, strong material that is excellent for windows. It does not warp, expand or shrink in the presence of moisture, as wood does. It is easy to cut and join together. It can be powder coated or anodized in the factory so that it never needs painting during its lifetime. It is also corrosion resistant.
The one drawback of aluminium is that it conducts heat rapidly, and so causes heat to be lost to the outside in cold climates. The solution for this is to design the window sections with a thermal break, or a layer of a non-conductive material that prevents the flow of heat.
2) Wooden Windows : Wood has been the material of choice for windows for many centuries. It is readily available, is easily worked on at site, and is a poor conductor of heat. Its drawback is that it is expands or shrinks with changes in moisture. This can cause windows to jam or warp. It can also decay in the presence of continuous moisture.Wood also needs painting or polishing to maintain its appearance.
3) UPVC and similar plastics Windows : Plastics are becoming increasingly common in residential windows. Plastics are light, do not warp, shrink, or decay, and have a reasonably attractive finish that does not need maintenance.
However, plastics are weak compared to aluminium or steel. This is why plastic windows are often reinforced with galvanized steel sections that are hidden within the plastic tubing. Plastics also have a high coefficient of thermal expansion, which can cause problems for windows.
Many plastics are also not resistant to UV light, a component of sunlight. Plastics in windows have to be specially formulated to ensure they do not become brittle, crack, or change colour during exposure to sunlight. this is called making materials UV stable. In general, plastic windows are cheaper than aluminium or wood.
4) Steel Windows : Steel is a very strong material, which allows steel windows to have the thinnest possible frames of all materials, maximising views. Unlike aluminium, it is difficult to cut and work, so site work has to be kept to an absolute minimum. Steel corrodes in the presence of moisture, so it must be galvanised or treated with a high quality moisture resistant painting process. Like aluminium, it is a good conductor of heat, so steel windows must have thermal breaks put in.
5) (GFRP) Glass-fiber-reinforced plastic Windows : GRFP windows are a recent addition to the range of window solutions. These are made of high quality plastics that are reinforced with glass fibers, giving them high tensile strength and stiffness. As such, they share a mixture of the good qualities of metals (high strength, low weight) and plastics (no warping, no corrosion, good finish).