Roofs are the most important covering of a structure, incorporating all structures and materials needed to support it on either the interior or on the exterior walls of the structure. A roof, like any other structural feature, is only as strong as its weakest link. The roof has loads and forces that cause it to break down in different ways depending on where it is positioned. If the roof is positioned on a slope, it puts concentrated pressure on the base of the roof, which weakens it at certain points. If the roof is located on an incline, it puts downward pressure on the roof and strengthens it at others.

A roof is a part of the overall building envelope, supporting many features which would otherwise be difficult to install or maintain. In urban climates, where temperature variations are the norm for most of the day, a roof is one of the few features that remain unaltered from day-to-day use. It may be exposed to extreme heat and cold, with the temperature of snow making some roofs collapse. In wetter climates where rain and moisture can cause extensive damage, roofs are also subject to damage from heavy rains and snow.

While residential roofs is differ in their composition, they share certain characteristics. They generally comprise concrete and gypsum-based materials such as gravel or crushed stone. The roof is then attached to the side of the house with the use of nails, screws, or rakes. For industrial buildings, metal roofs are common. For both residential and commercial buildings, the structure is typically supported by concrete posts and beams.

Residential roofs is vary greatly in their composition, from individual slates to intricately designed composite systems. The roofing system is often designed to maximize space efficiency, with skylights, hanging eaves, and landscaping incorporated into the design. However, no matter the design, the roof needs to be water resistant and strong to protect the structure from weather damage. Simple roofs are made out of clay tiles, which are quite strong and waterproof. However, slate roofs are particularly energy efficient, and it is possible to find a combination of clay and slate roofs in residential structures.

Commercial roofs vary greatly in design and materials, as they are used to support the entire building envelope. While the roof structure is usually metal or some other solid material, the materials themselves do not have to be. For example, shingles made from asphalt slates are an incredibly durable roofing option, and they provide excellent resistance to weather. However, asphalt shingles are a rather expensive roofing option, and this expense drives up the cost of roofs. In this case, composite materials like fiberglass would be the more affordable roofing option.

Another consideration when choosing a particular roofing system is whether or not the roof will be visible from neighbors' homes and on public street views. Most roofs are designed to blend in with the general appearance of the surrounding area, but some materials like slate can be very eye-catching and require little maintenance. In this situation, using less eye-catching roofs may be a better solution in terms of cost and appearance. It is important to remember that certain building codes can require certain materials like slate roofs to be clearly visible from a certain angle, and if this is not taken into consideration, the entire roof can become legally considered a roof covered structure.