Types of Truss Rafters
Truss rafters are engineered structures for carrying roof loads and materials. Trusses have been built in numerous sizes, shapes and materials. Today, these roof members are commonly made from wood or steel, and are usually only made to fulfill a handful of different roof designs. Does this Spark an idea?
Other People Are Reading
-
Common Truss
-
The common truss is a basic roof structure composed of one flat bottom chord and two equally sloped opposing top chords. This is a popular truss type that is used for buildings with gable roof structures and flat ceilings. The frame webbing design on the common truss can vary, and can even be exposed if built with specialty lumber.
Scissor Truss
-
The scissor truss is similar to the common truss in that it is also built with two equally sloped opposing top chords, but this type is built with two bottom chords that are also equally opposed, but with shallower slopes. This truss design is also used for gabled roof buildings, but the sloping bottom chords allow for vaulted ceilings.
-
Parrallel Truss
-
The parallel truss is mostly similar to the scissor truss as it is designed for use in gable roof applications with vaulted ceilings. The difference between the two comes down to their construction; the top and bottom chords on the parallel truss run parallel to each other for steeper ceiling vaults.
Flat Truss
-
The flat truss is designed specifically for use with flat and parapet roof structures. Though it is called a flat truss, the top chord will actually have a slight slope of 1/8 or 1/4 inch per foot, and can also be made with two equally opposing slopes for long spans. These trusses will only allow a flat ceiling as they are built with a flat bottom chord.
Mono Truss
-
The mono truss looks like half of a common truss, having only one sloping top chord and the horizontal bottom chord. These trusses can be used for the structure of a shed roof, but will most commonly be used perpendicular to common trusses to complete a hip type roof.
Other Truss Types
-
Other truss designs include the dual pitch truss, which is composed of two different opposing slopes; these were most popular in the 1970s, and are not common for new structures.
The Polynesian roof truss is built with four equally opposing slopes (two per side); the steep upper top chords meet midway in the span and continue to a shallower slope to the end. Along with the dual pitch truss, this roof type is also not commonly used in today's U.S. building industry.
-
