Construction Material

Girder Truss

A girder truss is a truss that spans a roof or other structure and is designed to carry a higher load than other trusses in the same construction. Additional plates and posts, in addition to those in standard trusses spanning the same distance, provide added strength against bending and shear. It could be employed, for example, when one roof structure meets another or where one structure abuts another, increasing the load at the girder truss position.

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Girder Truss

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What is a Girder Truss?

The design of girder trusses is long and straight. They have a top chord and a bottom chord, with diagonal and vertical webs separating them. The top chord is in compression all of the time, whereas the bottom chord is in tension all of the time.  Depending on their direction, the webs might be in tension or compression. In the truss depicted below, the diagonal webs are in compression and the vertical webs are in tension.


Girder Truss
Girder Truss by Vermont Timber Works (USA)


Timber girder trusses are ideal for large structures and look fantastic when combined with steel joinery. A girder truss’ primary function is to support other structural elements in the frame, such as standard trusses, rafters, and purlins. As a result, girded trusses are built to be extremely robust and stiff.


Its Function in Construction

A girder truss is a type of secondary roof support that is most commonly used in the construction of buildings that have a roof that is irregularly shaped. Its main function is to support the weight of the roof.

Typically present in L- or T-shaped buildings due to the fact that the roof changes direction at a sharp angle. Typically, it is constructed of wood, although stronger materials, such as steel, are often used. A secondary function of a girder truss is to provide structural support to both the roof and the adjoining walls and help buildings withstand hurricanes and other powerful forces.

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