Timber Framers Guild Forums Tools Timber Engineering Sizing a timber for a 38' horizonal span?

Hello Everyone,

I am trying to size a timber for a 38' horizontal span with a king post in the middle. I have the timber set at 10" wide. I was hoping for suggestions and comments from other timber framers on such a thing.

Thank you,
Ford Hall

More details? Joinery decisions? Loads applied? Number of bents? Spacing of bents And more questions. I sometimes base it on what shows up on the log truck, as an added input. I have 7x9's at 30', no joist pockets. Tim

Let me work out more details on this. I will get back this week.

Thank you, Ford

Hello Tim,

Thank you for your input. I have come up with these details thus far. What other details can I offer?

This structure is 38'x60'; 6/12 hipped roof; post are 10"x10"x10'; wood species is Greenheart and Tatabu; loads include 3" wainscoting, metal roofing and hurricane force winds. I imagine two main roof trusses. Each positioned roughly 22' apart at the hip to main roof intersection. The trusses will have two rafters (10"x12"x21'), a king post (10"x10"x11') and a tie beam spanning the 38' width. The rafters will join into the 38' tie beam. No decision has been made yet about bent or plate system. The wood can be sized accordingly. Ford

Ford, where do you live. Greenheart and Tatabu sound exotic. Hurricane winds point to the South. NC.

Is the building an open ceiling or is there a floor going in at the eve line? 20' sounds like a stretch, maybe a third truss in the center. Dragon beams at the corners, for the hips? Can you get 10x10x38' from the species you listed? Purlins? English Tying joint? Back to the open ceiling, if there is no floor or ceiling then there is no call for joinery on the tie and so it could be sized smaller if needed, due to the size of the logs. A large timber just adds weight to the truss. 10x10 aren't all that big. Lets see if anyone else has some comments.

I am just starting a 20' truss system tomorrow morning, using 9x9's, mostly because they sawed out nicely. I even had an extra which I hope I don't need. Tim