Bobtail Truss
A plated timber bobtail (stub) duopitch truss: the left support is set in from the normal heel by a cut-back, so the tie ends in a vertical and a diagonal that carry the rafter overhang, with a Fink web layout between; drawn as members without connector plates. Span between the supports, pitch and overhang, Cut-back of the left support from the normal heel, Member thickness and chord and web depths
Details
Category: Roof Framing › Straight Truss Roofs › Timber Trusses
By Huu Khanh Nguyen · Updated November 4, 2026
Parameters
| Name | Default | Unit |
|---|---|---|
| Span | 9000 | mm |
| Pitch | 31 | ° |
| Overhang | 450 | mm |
| Member Thickness | 35 | mm |
| Chord Depth | 97 | mm |
| Web Depth | 70 | mm |
| Slope | Math.tan((pitch * Math.PI / 180)) | |
| Heel Height | chordDepth / Math.cos((pitch * Math.PI / 180)) | mm |
| Cut Back | Math.max(0.08 * span, (chordDepth + webDepth) / slope - webDepth) | mm |
| Width | span + 2 * overhang | mm |
| Depth | chordThickness | mm |
| Height | (span / 2 + cutBack / 2 + overhang) * slope + heelHeight | mm |