Types of Trusses
This is the most common style of roof truss and is used for many Commercidal, Residential and Farm applications.
The layout of the webs will vary depending on the span and loading. The normal span range is 10′ to over 60′, with roof slopes ranging from 2:12 up to 12:12. Long spans (over 50′) with low roof slopes (under 4:12) are not recommended as the chord forces at the Heel becomes extremely high. The Designer should select a Sloping Chord Flat Truss instead.
These trusses are designed to provide a flat roof appearance with the true economy of a truss system. They are often used in mansard type roof applications, and are usually built with a slight top chord slope to create positive roof drainage.
As floor trusses, Flats may be built with the chords and webs oriented in one of two ways.
Deflection considerations are more critical with Flat Trusses than with Pitched ones, and a span to depth ratio of 22 is the recommended maximum.
Many special shapes and structures may be fabricated taking advantage of the roof truss systems.