Hip roof
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A hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a house with no gables or other vertical sides to the roof. A square hip roof is shaped like a pyramid. Hip roofs on rectangular houses will have two triangular sides and two trapezoidal ones. Hip roofs often have dormers.
Hip roofs are more difficult to construct, requiring somewhat more complex systems of trusses. They have the advantage of giving a compact, solid appearance to a structure. In modern domestic architecture, they have been seen to represent comfort, practicality, and solidness. They are thus commonly seen in bungalows and cottages, and have been integral to styles such as the American Foursquare. However, the hip roof has been used in many different styles of architecture and in a wide array of structures.
A mansard roof is a variation on a hip roof, with two different roof angles, one much steeper than the other. A tented roof, popular in Russian architecture, is a steep hip roof, often with multiple angles. Another variation is the Dutch hip roof, which has the two sides at a gentler angle than the front and back, the vertical distance between the sides and front is made up by small gables in the middle of the roof.
A hip roof on a rectangular plan has four faces. They are almost always at the same pitch or slope, which makes them symmetrical about the centerlines.
Hip roofs have a consistent level fascia, meaning that a gutter can be fitted all around.
Although the roof itself is harder to construct, the walls that carry the roof are easier to build, being all one level.
A hip roof is self bracing. It does not need the same amount of diagonal bracing (wind bracing) that a gable roof requires. It holds up much better to high winds. In areas like Northern Australia, or the Gulf Coast of the Southeastern United States, that are subject to high wind loadings and strict construction codes this could be a factor in deciding which type of roof to build. The hip roof also exhibits increased survivability in tornadic winds.
The overhang of the roof at the walls is called the eaves. The eaves of a roof perform valuable functions apart from the looks. They protect the walls from the weather and help to shade the walls (and the windows in them) from the sun, reducing the power needed to cool the structure. A hip roof therefore helps to shade all of the walls of the building, unlike a gable roof which has minimal overhangs at the gables.
A possible disadvantage of a hip roof compared to a gable roof on the same plan, is that there is less room inside the roof space. Access is more difficult for maintenance.
Hip roofs can be constructed on a wide variety of plan shapes. Each ridge is central over the rectangle of building below it. The triangular faces of the roof are call the hip ends, and they are bounded by the hips themselves. The hips sit on an external corner of the building and rise to the ridge. Where the building has an internal corner a valley makes the join between the sloping surfaces.
A hip roof is also ideal to have in hurricane regions, especially if the slope of the roof from horizontal is 35 degrees or greater (to reduce/eliminate the airfoil effect of extreme high winds that blow over the roof) as they are far less likely to peel off the house than a gable end roof. To this end, since 2001 the State of Florida has required windstorm insurance companies to offer a premium discount to customers who can prove they have a hip roof, which they do by obtaining a windstorm inspection.
A cross between a gable and a hip roof is a dutch gable. It simplifies the construction of the roof. No girder trusses are required, while still retaining level walls and consistent eaves.
