Rafters, joists and jacks are the basic elements required to build a roof frame. Specialty companies manufacture A-frame trusses in various shapes and sizes and calculate loading requirements and stresses for each design. Builders use numerous trusses to make roofs, including scissor trusses for vaulted or cathedral ceilings, room-in-attic trusses for houses with living space in the attics, clerestory trusses for high walls with narrow windows at the top, and triple howe trusses for spans from 54 to 80 feet.
Most roofs are pitched or angled. The most common types of pitched roofs are gabled, hipped, shed and mansard. A gabled roof slopes around a triangle shape at the end of a wall. A hip is the joint between two adjacent portions of the roof, and complex designs may include several hips on one hipped roof. Shed is a simple roof design with only one slope, and homeowners commonly use this for additions to an existing structure or lean-tos. Mansard roofs have living areas under the roof space.
Portions of pitched roofs meet at ridges, hips or valleys, depending on the design. These points are where the roofs change directions. The edges of the roofs may be verges, abutments or eaves. Eaves are between the roofs and the walls, and verges are between gabled roofs and the walls.