Roof Truss Terminology Pdf

Quite common until the 1920 s the function of a roof truss is to support the purlins.

Roof truss terminology pdf.

Trusses of the roof are not entirely independent as in a common rafter roof but connected and supported by longitudinal members. A truss is a frame that supports loads by efficiently transferring its forces to end supports. A purpose designed tile that covers the ridge of a pitched roof. A sheet metal or pvc profile attached at the end of the overhang of the roof trusses to catch rain water runoff from the roof figure 3 heel.

A roof s slope is the number of inches it rises for every 12 inches of horizontal run a roof with a 4 in 12 slope rises 4 inches for every 12 inches of horizontal run. Slopes at roof pitch. The terms pitch and slope are simply two different ways of expressing the same measurement. In the following section we ll cover some of the more common roof and rafter terms you ll need.

All truss designs are optimized to provide the most economical application. The following glossary assumes that longitudinal is the direction in the ground plan which runs parallel to the ridge while transversal is the direction. While stick framing might use larger 2x8 2x10 etc. Members which are expensive and might require either additional beams or interior load bearing walls trusses can span a longer distance without additional supports while using less expensive members.

Trim along the edge of roofing at a gable end. Framing terms knowing the basic vocabulary is a necessary part of your work as a builder. Truss terminology bearing width the width dimension of the member providing support for the truss usually 31 2 or 51 2. Truss terminology technical terms used in the truss industry may not be familiar.

Cantilever that structural portion of a truss which extends beyond the support. Roof framing terms are related to the parts of a triangle. The full use of this advantage is achievable if the height of the truss is not. 1 4 aspects of truss design for roof structure 1 4 1 truss or i beam for the same steel weight it is possible to get better performance in terms of resistance and stiffness with a truss than an i beam.

A truss that supports other trusses beams or rafters figures 1 2. The highest point on a truss. Some of the more common are listed below and are illustrated on pages 3 4. Sometimes found in very large buildings where big rooms resulted in few load bearing walls.

Standard roof truss configurations parallel chord 4x2 floor truss with chase 2x4 floor or roof truss can design with a chase as well are determined by span load and spacing. Bearing must occur at a truss tjoint location. Roof features associated with basic roof framing terms are shown in figure 2 2. The part of a truss where the top chord and bottom chord intersect figures 3 6.

This difference is more sensitive for long spans and or heavy loads. The parallel chord or fl at truss gets its name from having parallel top and bottom chords. The same roof has a 4 12 or 1 3 pitch.