A roof is usually the top surface of a structure, comprising all structures and materials required to support it upon the ground of the structure or on uprights. In its simplest form a roof is made up of concrete slabs attached by ties to the roof rafters. Roofs have been in use since ancient times, where they were used as covering for tombs, temples and other buildings. As such, there are many different types of roofs, each with its own practical and aesthetic value.
A basic roof structure consists of a single slab of concrete, attached either via the use of shingles or tied to be held in place with nails. The slab is then covered with a polyethylene layer that acts as a protective layer against moisture, and heat. An inner layer of insulation is also included to trap heat within the house. The outer layer, which is often referred to as the attic insulation, is a thin sheet of metal, designed to reflect solar heat and to keep warm indoor temperatures at bay. All the main articles of a roof structure are made of metal, with wood often only acting as a protective layer against the elements. Roofs are commonly constructed in two distinct styles, one with a ridgepole, which is used to attach the main article to the rest of the roof structure, creating the ridgeline; and the other type, known as a box joint, in which each main article is connected directly to the rest of the roof.
As the name indicates, flat roof shapes are made using two long beams or horizontal rafters that form an overhanging style from which a single, longer beam is suspended. There are a number of different flat roof shapes, but their main advantage is that they are relatively simple to construct, relatively cheap to build, and easily assembled on site. The main drawback is that the flat roof places a great deal of stress on the supporting structure. If the supporting structure becomes damaged, or even if the roof itself develops minor cracks, then the whole roof could become damaged, with nothing being left to act as a support for the rest of the roof. For this reason it is important to ensure that all the rafters, beams and other parts of the roof are regularly inspected and maintained by trained professionals.
Medium pitch roofs are a hybrid of low pitch and flat roofs. Unlike low pitch roofs, medium pitch roofs feature an overhanging design, with the height of the roof increasing along the pitch. The pitch can be increased to provide an extra level of water resistance, or it can be decreased to allow for greater exposure to sunlight. This is achieved by adding either metal roofing material or a thicker sealant, such as an epoxy.
High slope roofs have several advantages over their low-pitch competitors. Firstly they feature a more pronounced slope, with more of the roof surface exposed to the elements. Secondly they are usually more resistant to both snowfall and rain. Thirdly, they do not need to be as tightly packed as low pitch roofs in order to effectively insulate against heat transfer. Lastly, they are more aesthetically pleasing than low pitch roofs, which is often seen as a negative aspect.
There are a number of different types of pitch used in residential roofing materials. Each type exhibits a unique property of its own, which increases its effectiveness at insulating against heat transfer and dampening the effects of sunlight. Slate is probably the most commonly found roofing material in North America, as it is the most widespread in residential applications. Slate also offers many advantages over other types of roofing materials, as it is extremely water and fire resistant. Slate can also add significant aesthetic value to a home, though this is largely unachievable due to its limited color range and grain patterns.