A queen post truss uses two vertical posts instead of one, with a straining beam between them, extending the span a king post can manage. Typical span: commonly 26 to 45 ft. Truss count comes from the building length rather than the span — divide the length by the spacing, add one, then add two gable-end trusses.
A queen post truss uses two vertical posts instead of one, with a straining beam between them, extending the span a king post can manage. This page gives the truss count at 24 and 16 inch centres, the rafter length and the ridge height for the spans a queen post truss is normally used at, along with what distinguishes it from a standard fink truss, where it fits, and the constraint that decides whether it will work on your building. Typical span: commonly 26 to 45 ft.
| Span | 4/12 rafter | 6/12 rafter | 8/12 rafter | 6/12 ridge height |
|---|---|---|---|---|
| 16 ft | 8.4 ft | 8.9 ft | 9.6 ft | 4 ft |
| 20 ft | 10.5 ft | 11.2 ft | 12 ft | 5 ft |
| 24 ft | 12.6 ft | 13.4 ft | 14.4 ft | 6 ft |
| 28 ft | 14.8 ft | 15.7 ft | 16.8 ft | 7 ft |
| 32 ft | 16.9 ft | 17.9 ft | 19.2 ft | 8 ft |
| 40 ft | 21.1 ft | 22.4 ft | 24 ft | 10 ft |
A queen post truss changes the webbing inside the outline, not the outline itself, so the rafter length and ridge height are the same as any other truss at that span and pitch.
Truss count comes from the building length, not the span. Divide the length by the spacing, add one for the final end, then add the two gable-end trusses.
| Building length | At 24 in centres | At 16 in centres |
|---|---|---|
| 24 ft | 15 | 21 |
| 32 ft | 19 | 27 |
| 40 ft | 23 | 33 |
| 48 ft | 27 | 39 |
| 60 ft | 33 | 48 |
Counts include the two gable-end trusses, which are a separate component from the commons and are ordered as such.
| Typical span | Commonly 26 to 45 ft |
|---|---|
| Best for | Medium spans where a king post runs out and a full webbed truss is unnecessary |
| Watch for | The straining beam between the posts is a compression member and its size matters |
A queen post truss uses two vertical posts instead of one, with a straining beam between them, extending the span a king post can manage.
Commonly 26 to 45 ft. The exact limit depends on the timber species and grade, the spacing, and the snow and wind loads for your area, so the truss designer sets it rather than a table.
Divide the building length in inches by the spacing and add one, then add two gable-end trusses. A 40 foot building at 24 inch centres needs 21 common trusses plus two gable ends.
No. Cutting, notching or drilling any truss voids its engineered design. If it does not fit, the answer is a redesign from the truss plant, not a saw.