Terms For Roof Truss Members

Saddle a covering on the ridge of the roof so that water will drain.

Terms for roof truss members.

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. The same roof has a 4 12 or 1 3 pitch. The terms pitch and slope are simply two different ways of expressing the same measurement. 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.

Truss members are made up of all equivalent equilateral triangles. Roof cap the total roof assembly members located above the wall line such as beams trusses plates purlins decking bridging ceiling roofing etc. The following diagram shows the terms applying to gable end roofs. 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. Components of a steel roof truss. 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. I upper chord members.

A percentage increase in the stress permitted in a member based on the duration of the load causing the stress acts on the member. There are two main types of timber roof trusses. A horizontal or inclined member that establishes the lower edge of a truss usually carrying combined tension and bending stresses. 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.

When a roof is to be provided for a building which does not have interior supports and the exterior walls are more than 12 m apart a roof truss will be a convenient arrangement to support the roof. Scupper an opening in a roof usually faced with metal flashing to drain water from the roof at a given point. A metal plate connected wood truss is a roof or floor truss whose wood members are connected with metal connector plates. The following diagram shows the terms used for general roof truss members.

4 2 design is used for shallow floor trusses. 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. Truss members form a series of equilateral triangles alternating up and down.