Terms For Roof Truss Members

A horizontal or inclined member that establishes the lower edge of a truss usually carrying combined tension and bending stresses.

Terms for roof truss members. Cantilever that structural portion of a truss which extends beyond the support bearing the cantilever dimension is measured from the outside face of the support to the heel joint. The top members of a truss are known generically as the top chord bottom members as the bottom chord and the interior members as webs. Closed in which the bottom chord is horizontal and at the foot of the truss and open in which the bottom chords are raised to provide more open space also known as raised bottom chord. The uppermost point of a truss.

In historic carpentry the top chords are often called rafters and the bottom chord is often referred to as a tie beam. Scupper an opening in a roof usually faced with metal flashing to drain water from the roof at a given point. Hangers connect carried trusses to the carrier or girder. Bearing width the width dimension of the member providing support for the truss usually 3 or 5 bearing must occur at a truss joint location.

A roof truss consists essentially of the following components. The following diagram shows the terms used for general roof truss members. Roof cap the total roof assembly members located above the wall line such as beams trusses plates purlins decking bridging ceiling roofing etc. Truss members form a series of equilateral triangles alternating up and down.

4x2 truss has its members have the nominal 2 face up for plate embedment the 4 2 truss is a nominal 4 deep rather than a nominal 2 deep. The following diagram shows the terms applying to gable end roofs. 4 2 design is used for shallow floor trusses. 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.

Truss members are made up of all equivalent equilateral triangles. There are two main types of timber roof trusses. A metal plate connected wood truss is a roof or floor truss whose wood members are connected with metal connector plates. The same roof has a 4 12 or 1 3 pitch.

Components of a steel roof truss. The terms pitch and slope are simply two different ways of expressing the same measurement. A percentage increase in the stress permitted in a member based on the duration of the load causing the stress acts on the member.