Truss Glossary and Terminology
|
Apex The highest point on a truss. Attic Truss A truss with an attic room space within the truss. The bottom chord doubles as the floor joist and the top chord as the rafter. Batten Roofing battens or ceiling battens. Usually timber members fixed at the truss chords to support roof tiles or ceiling material. Also provides lateral restraint to the truss. Bearing / Support Point Point at which the truss is supported. A truss must have two or more supports located at truss panel points. Bottom Chord Truss member forming bottom edge of truss. Butt Joint Splice End-to-end joint between two pieces of timber. Cantilever That part of a truss that projects beyond an external main support, not including top chord extensions or overhangs. Chord The truss members forming the top and bottom edges of the truss. Concentrated Load A load applied at a specific position. e.g. load applied by an intersecting truss. Connector Light gauge steel plates with teeth projecting form one face. When pressed into intersecting timber members the plate connects the members in a rigid joint. Creep Movement resulting from long-term application of load to a timber member. Dead Load Permanent loads due to the weight of materials and truss self-weight. Deflection Movement in a truss due to the applied loads. Design Loads The various loads that a truss is designed to support. Distributed Load Loads spread evenly along truss member. Fascia Trim along the edge of the eaves. Gable Truss Standard triangular shaped truss with Verticle webs. Girder Truss Truss designed to support one or more trusses. Heel Joint The joint on a truss where the top and bottom chords meet. Heel Point The position on a truss where the bottom edge of the bottom chord meets the top chord. Hip Intersection of two roof surfaces over an external corner of a building. Hip Roof Roof constructed with rafters or trusses pitched over all perimeter walls. |
Jack Truss Half truss and part of family of trusses that makes a hipset. King Post Vertical web at the centre of a gable truss, or the vertical web at the end of a half gable truss. Lateral Brace Bracing restraint applied at right angles to web or chord to prevent buckling. Longitudinal Tie Bracing restraint applied at right angles to web or chord to prevent buckling. Live Load Load as a result of occupancy or use of the building. Overhang Extension of top chord beyond support. Provision of eaves on gable trusses. Panel-point The point where several truss members meet to form a joint. Panel-point Splice Splice joint in a chord coinciding with web intersection. Pitch Angular slope of truss chord measured in degrees. Purlin Roofing purlins. Usually timber members fixed at right angles to the truss chords to support roof sheeting. Also provides lateral restraint to truss. Similar to battens except more widely spaced. Rafter A roof member supporting roofing battens or roofing purlins in conventional construction. Rafters employ only the bending strength of the timber. A roof truss may also be called a trussed rafter. Ridge The highest point on a gable roof. Setback The position of a truss measured from the outside face of the end wall. Usually used to describe the position of Truncated Girder and Standard trusses in a Hip End. Span The horizontal distance between the outer edges of the truss supports. Span Carried The span of standard trusses that are supported by a girder truss. Stub Truss Description of a truss based on standard shape but which is cut-off short of its full span. Top Chord Truss member forming top edge of truss. Truss A framework of members forming a light, strong, rigid structure. Usually a triangulated structure. Valley Intersection of two roof surfaces over an internal corner of a building. Valley Truss or Saddle Truss Part of a set of non-structural trusses to form valleys. Web The internal members of a truss. Usually only subject to axial loads due to truss action. Wind Load Load applied to the roof by the wind |