Only seven different types of roof rafters are required to build the most complex roof. A simple gable roof
can be constructed using only one type, the common rafter. Three
different types the common, hip, and hip jack rafters are all needed to
frame a hip roof.
These rafters can be cut from standard framing lumber, laminated veneer lumber, glued laminated beams, timbers, steel, or I beams made from wood called TJI's.
Types of Rafters
Common Rafters are found in all conventionally framed roofs and run from an exterior
wall all the way up to the ridge board. They are used to set the height
and center the ridge board in the span. After the ridge board location has been established the hip and valley rafters location can then be be established.
Hip Rafters run at a 45 degree angle to the commons and are placed from the outside corners of the building to the ridge board.
Hip Jacks sit on the outside walls and run up to the hip rafter in line with the common rafters.
Valley Rafters are placed at inside corners to the ridge and are also at a 45 degree angle to the commons.
Valley Jacks run from the valley rafter up to the ridge board and in line with the commons.
Cripple Jacks are used when a valley and hip are located close together and only go from a valley to a hip rafter.
Flying Hip also known as a mystery hip go from where a valley rafter meets a ridge to the end of a higher ridge board.
The illustration below may give you a better idea of where the different types of rafters are located when framing a roof.