Types of Gable Trusses

Triangular

• Triangular trusses--also known as common or gable trusses--are some of the most common types of trusses used in roof construction. They are characterized by a horizontal base chord and two top chords that angle inward so that they complete a triangle. These trusses can further be distinguished by the arrangement of their webs. According to the Canadian Wood Council website, while a king post truss has just one web running vertically down its center, a Howe truss includes two other webs (which form small triangles) on either side of its center web. A Fink truss has no center web, and instead uses webs to form a W shape, which holds up its top chords.

Attic

• An attic truss is essentially an entire, all-in-one gable frame, which includes the roof. According to the Canadian Wood Council, it provides a useable space within the truss itself, using the base chord as the floor. While the top chords angle inward just like in a triangular truss, the attic truss features two perpendicular webs that run upward and meet a horizontal web, which is parallel to the base chord. This forms a square outline, which will eventually be the room.

Gambrel

• According to the Canadian Wood Council, you can use a gambrel truss to create a barn-like roof for your gable. The webs of a gambrel truss form a crown shape, with two triangles or spikes on either side of a center beam. The chords form the shape of a bisected octagon (if you start from one the of points or angles of the octagon).

Hip

• Hip trusses, like gambrel trusses, have crown-like web structures, which form two spikes on either side of a center beam. However, while a gambrel truss resembles a bisected octagon, a hip truss resembles a bisected hexagon. The overall shape of the truss is a trapezoid, as the base and top chords are parallel to each other.

Scissor

• Scissor trusses are commonly used for framing cathedral ceilings, however, they can also be used to create large and unique gable designs. According to RafterTales.com, the lower chords of scissor trusses are not horizontal like in the majority of gable trusses (such as triangular, gambrel, and hip trusses). Instead, they are angled inward (or upward), making the overall shape of the structure resemble a kite or hang glider.

Multipiece

• According to RafterTales.com, multipiece, or piggyback trusses, are essentially two trusses stacked one on top of the other. This is usually done so trusses can be more easily transported and otherwise managed. Typically, a multipiece truss will feature a small triangular truss on top of a hip truss.