What are Pitched Roofs?
Pitched roofs are roofs that slopes downward in two parts at an angle from a central ridge, so as to leave a gable at each end. Most roofs are pitched. There are many types of pitched roofs to suit different situations. As a result, there are many variations on the basic design and numerous combinations of design elements with construction methods.
Roofs are usually defined according to their shape and there are many variations on these themes. Each type can be built with different materials and different ways.
- Gabled – The roof slopes around a triangular extension of the end wall. Gable is this piece of the wall..
- Hipped – A hip is the joint between two adjacent slopes of a roof. Some complex roofs have several hips.
- Shed – This simple roof has only one slope. It is commonly used on lean-to structures, such as additions.
- Mansard – A modified version of the pitched roof that creates a spacious living area in the roof space.
Pitched Roof Frames
A pitched roof has a network of frames to support the structure and its covering. Two main types of wooden frames are a trussed roof and a cut roof— which are sometimes combined to achieve more complex roofs. Both types of construction will support any common roof coverings.
Common Trussed Roof Frame
Often referred to as A-frames because of their shape, modern trusses (lumber frames) are manufactured off-site by specialist companies. The A-frame combines rafters, joists and jacks. Several A-frames make up a roof. Because of technological advances in calculating the stresses and loading requirements of roof lumber, trusses can be made slimmer than the boards in a cut roof. Trusses are manufactured in a number of different shapes and sizes to suit the needs of various types of roofs. For example, some trusses are designed to leave a lot of open space in a roof, so that it can be used as a room. Lean-to, or shed, trusses are commonly used for additions.
Cut Roof Frame
Traditionally, all roofs were “cut” — carpenters cut rafters on site during construction. To cover greater spans, some of the roof’s weight may be transferred onto internal loadbearing walls using purlins (beams that brace the rafters). This forms a “double” roof. Although they are labor-intensive, single- and double-cut roofs are still constructed.