Cold-formed steel trusses can be broadly categorized into pitched and parallel chord trusses. Within these categories, different shapes and structural configurations can be designed, including gable, hip, vaulted, inline, back-to-back, stiffened chord and box chord trusses, depending on the requirements of the building.
Cold-formed steel (CFS) trusses use steel members connected in a triangular network to distribute loads through the truss joints. Different truss types and configurations allow CFS systems to accommodate a range of roof, floor and ceiling applications.
Understanding these different types is an important starting point when considering how a CFS truss system can be designed for a project.
CFS trusses can be divided into two basic types: pitched trusses and parallel chord trusses.
| CFS truss types | Configuration | Typical application |
|---|---|---|
| Pitched truss | Triangular form with a single or dual roof pitch | Roof construction |
| Parallel chord truss | Top and bottom chords run parallel to each other | Floor and ceiling construction |
Pitched trusses are the most common type used for roof construction. Parallel chord trusses, sometimes referred to as flat trusses, provide a different configuration suited to applications where the upper and lower chords need to remain parallel.
Within these broad categories, CFS trusses can be designed in different shapes to suit the geometry of the building.
Gable truss: A pitched configuration with two sloping sides meeting at a central ridge.
Hip or truncated truss: A pitched truss with a truncated upper section, used as part of a hip roof configuration.
Parallel chord truss: A flat configuration in which the top and bottom chords remain parallel.
Scissor truss: A pitched or parallel chord truss with an inclined (sloping) bottom chord forming a higher/vaulted ceiling as required.
Cold-formed steel trusses can also differ in how their members are configured and reinforced. FRAMECAD truss systems include several configurations designed for different structural requirements.
| CFS truss configuration | How it differs |
|---|---|
| Inline truss | Standard truss configuration with a large bearing area at the supports |
| Stiffened chord truss | Inline truss with one or more chords stiffened for longer spans or to support higher loads |
| Box chord truss | Inline truss with boxed chords for longer spans or higher loads |
| Back-to-back truss | Strong-axis bending truss configuration |
| Box-section reinforced back-to-back truss | Back-to-back truss with boxed chords for longer spans or higher loads |
| Floor Truss | Engineered parallel chord truss designed for efficient production and assembly |
Stiffened and box chord (or nested) configurations can be used where longer spans or higher loads need to be accommodated. The appropriate configuration depends on the structural requirements of the project.
One important distinction between cold-formed steel truss configurations is the orientation of the steel profiles.
An inline truss uses a minor-axis orientation, where the top and bottom chord members are framed in the horizontal plane. This provides a larger surface bearing area at the supports, which can simplify assembly and installation.
A back-to-back truss uses a major-axis or strong-axis orientation. With the top and bottom chord members framed in the vertical plane, the configuration provides greater load-carrying capability and can accommodate longer truss spans.
The appropriate CFS truss type depends on the geometry, architectural, and structural requirements of the project.
Truss shape, member orientation and connections can all influence how a truss performs and the span it can achieve.
This means truss selection should form part of the engineered design of the complete structure rather than being based on shape alone.
If you would like more information about cold-formed steel systems, please reach out to our team.