Roof Trusses Manufacturers Terminology – Components of a Truss

 

Roof-Terminology4

APEX (Peak): The highest point on a truss where the sloping top chords meet.

BEARING: Structural support of trusses (usually walls), normally with a timber wall plate.

BEARING CUT or SEAT CUT: A horizontal cut to the bottom of a sloping bottom chord, usually the width of the bearing, i.e. the wall plate width (see Figure 7).

BUTT CUT: A slight vertical cut (usually less than 75mm) at the outside edge of a truss’s bottom chord to ensure the correct height over the wall plate (see Figure 5).

BOTTOM CHORD (BC) or TIE BEAM: Horizontal or sloping member that establishes the lower edge of a truss and usually carries combined bending and tension stresses.

CANTILEVER: The part of a structural member that extends beyond its support (see Figure 5).

CANTILEVER STRUT: A web that joins the bottom chord above the bearing point to the top chord of a cantilevered truss (see Figure 5).

CHORD: One of the main members that form the outline of the truss and that are subject to relatively large axial forces and bending moments.

CLEAR SPAN: The horizontal distance between interior edges of supports.

HEEL: The point on a truss at which the top chord and bottom chord intersect.

JOINT: Point of intersection of one or more web(s) with a chord.

NAIL PLATE: A galvanized steel plate punched to form a nail pattern integral with the plate and used to connect timber members.

NODE (Node-Point): A point of intersection of two or more members that make up the panels of a truss.

NOMINAL SPAN: The horizontal distance between the outside edges of the supports (wall plates) – usually the tie beam length.

OVERHANG: The extension of the top chord of a truss beyond the bearing support.

PANEL: A truss segment defined by two adjacent joints or nodes.

Roof-Terminology5

PLUMB CUT: A vertical cut to the end of the top chord to provide for vertical (plumb) installation of the fascia or gutter (see Figure 4).

SPLICE POINT: The point at which two chord members are joined together to form a single member.

SQUARE CUT: A square cut to the end of the top chord, i.e. perpendicular to the edges of the chord (see Figure 5).

STUB END: The end of a truss that is trimmed back so that the top and bottom chords do not meet at a heel but are separated by a vertical member (see Figure 5).

TOP CHORD (TC) or RAFTER: The sloping or horizontal member that establishes the upper edge of a truss.

TRIANGULATION: Webs and chords forming triangles to ensure the stability of a structural frame such as a truss.

WEB: A member that joins the top and bottom chords of a truss, to form a triangular pattern. Webs may carry tensile or compressive forces, depending on their position in the truss.

 

Roof Trusses Sundry Timbers Connected To Trusses | Roof Trusses Terminology – General

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