The roof is one of the most important parts of any structure since it serves to protect the interior from the outside weather and climate. Roof designs are expected to survive the trials of time and weather, and some ancient designs are even commonly today used for a variety of applications.
On a hip roof, all sides slope down from the roof ridge to the walls in a number of possible slopes. This is a common roof type since it is easily designed and constructed. Hip roofs are built with eaves on all sides of the structure, offering shade and weather protection for all walls. This roof design is applicable to just about every floor plan and house type.
A gable roof is similar to a hip roof, but only has two opposing sloped surfaces closed off with vertical walls at either end. This has grown to be a very popular roof choice because of how easy it is to construct and since it can offer more open space for an upper floor or an attic. The gable roof has been used throughout history, notably in ancient Greek and Roman architecture.
A saltbox roof is very similar to a gable roof, as it has two opposing sloped surfaces. The saltbox is seen on multi-floor buildings, and has an asymmetrical profile. The slope on the front of the structure covers the top floor, and the rear slopes cover both the top and bottom floor. This type of roof design originated in New England, and is mostly seen in American colonial architecture.
The bonnet roof is a variation of both hip- and gable-type roofs. This type of roof utilises the simplicity of hip and gable roofs, and adds a secondary slope that joins to the main structure's roof. The bonnet roof is usually used to cover a wraparound patio or deck, and offers more protection from weather like rain and wind than other roof types. This type of roof has been most commonly used in colonial architecture seen in the Southern states.
The flat roof is a cost-effective and easily constructed roof type. This type of roof bares little slope, and is usually coated with tar and gravel. The flat roof is most commonly seen with an accompanying parapet wall, which is a wall that extends the height of the roof, and can be used to screen any equipment that is placed on the roof. The flat roof is commonly seen in Southwestern and multifamily architecture. The nature of this roof design type offers a good platform for green roof building and rooftop gardens.
The mansard roof is an alteration of the hip roof, and bares two different slopes on each roof surface: the standard slope on the top part of the roof and a much steeper slope extending to the structure wall. This design was made popular in 17th century France, and can still be seen today on historic homes and commercial buildings like Pizza Hut and some McDonald's restaurants.
The gambrel roof is most recognisable on the American barn, and resembles a marriage of both gable and mansard roof types. The gambrel has two opposing slopes like a gable, but each side has multiple slopes as it gets closer to the structure walls, like a mansard roof. Though this roof design is most commonly seen on rural barns, it has been adapted to fit homes as well.