It is also argued that glazing is a very aesthetically pleasing material that can be used in construction. Not only it is aesthetically pleasing but there is a range of shape, sizes thicknesses and colours that can be used making it a versatile material offering a range of benefits. Not only that but glazing is such a strong material it can now be used structurally. Some people may argue that having too much glazing can be costly to maintain as the windows will need regular cleaning which means a window cleaner may have to be hired. However this problem can be overcome easily by using self-cleaning windows. The self-cleaning windows are covered in a special coating which reacts when it is exposed to sun light. The coating then breaks down the dirt which means it does not stick to the window, so as soon as there is rainfall, the dirt is washed into the gutters.