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Steep Slope Trusses

Steep Slope Trusses

Has anyone ever come across a job where the pitch of the top chord of the truss exceeds 12/12? I'm looking for shop drawings or samples of trusses with steep slopes ie. 14/12, 16/12 pitch.

A confused student is a good student.
Nathaniel P. Wilkerson, PE

RE: Steep Slope Trusses

Yeah, but not many. They get awfully tall awfully quick.

RE: Steep Slope Trusses

Just had one more thought you might find some value in.

Truss programs throw webs in based on a horizontal projection. (An 8' horizontal projection is pretty typical around here) So on steeper trusses you can get some pretty long chord segments measured along the rake. At time I've had to add in another panel pint on steeper trusses just so the chord segments aren't too long.

RE: Steep Slope Trusses

16/12 scissor truss with a 18" raised heel. Note the configuration of the heel web and bottom chord at the bearing point.

I'd hate to the be the roofer on a pitch this steep.

A confused student is a good student.
Nathaniel P. Wilkerson, PE

RE: Steep Slope Trusses

It was finished with slate shingles. The trusses were 2ply at 16" O.c. to control deflections. The builder asked me if I could design a fix as they wanted to cut out the bottom chords of two trusses to make way for one of the those ceiling mounted whole house fans -after the roofing was installed mind you. I literally told him to get lost, or something line that, after I finished laughing. I had already gone 2 months around and around on the shop drawings just to get to that point. To be fair, it was the builder project manager who was insisting/asking. The builder foreman was wiping the sweat off his brow and had a nice smile when I said it.


RE: Steep Slope Trusses

Definitely not your run of the mill garage truss package. Quite a bit more interesting than the typical trusses that I usually look at in any given job in my neck of the woods, but then again I don't get to do very many large residences.

When I look at the complexity and crazy configurations of some of these truss profiles I am amazed that the software (Mitek in this case) is able to handle it. I've actually never used any of these mainstream truss software packages so I have no idea how easy or difficult they are to use but it would seem that even with the best software in the world a complex truss package would still be a lot of work putting it together.

A confused student is a good student.
Nathaniel P. Wilkerson, PE

RE: Steep Slope Trusses


Again thank-you for sharing some of your truss data. Based on it I was able to extend my scissor truss module to include truss profiles that are as steep as 18/12 on the top chord pitch and 12/12 on the bottom chord pitch. I can also use this algorithm on a number of similar truss types (mono cathedral, cambered etc...)

A confused student is a good student.
Nathaniel P. Wilkerson, PE

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