Hip Roof Design on a two port garage, no manufactured trusses

[ing.torres303]

Hi everyone, i wanted to get some knowledge out of you folks in regards to the design of a 26ftx30ft garage hip roof. We did the design for the overall structure and had noted on plans for the roof trusses to be by others. We recently got received an email from the contractor and the owner requesting for us to design the trusses as they did not want them to be manufactured trusses. The span length is the 26ft, and the ceiling joists are not going to work. I got the idea that we would need to design our own trusses, but even at that point the truss layout is something I'm not too familiar with. Does anyone have any resources, design guides or sample calculations that i can study in order to see if it would be possible for us to design this? TIA!

 

[Pmtottawa]

That is a big span for diy built trusses. For smaller spans I designed triangulated trusses with plywood gusset plates.

May not work for your spans though

 

[XR250]

Why not use two beams and standard rafter framing? You can use the beams to support the ceiling joists and hips.
No one in my market wants to pay me to design a site-built truss for this situation.

 

[Eng16080]

One option is to have two trusses at the locations where the hips and ridge intersect, with a structural ridge beam between them, and 4 structural hips. Like this:

Both trusses are the same, so you're only designing a single truss. The rest is just stick framing. The trusses are supporting the entire interior of the roof and will likely require engineered lumber to work.

Will this be cheaper/easier than using manufactured trusses? Probably not, but it's a reasonable alternative.

 

[RontheRedneck]

No pre-manufactured trusses ????? That's some sick, twisted stuff right there.

If I was doing trusses for that job, I'd use a shorter setback to the hip girder. We typically do less than 8'. Then the jacks are easier to build, and we don't need larger hangers.


However you do it, I'd suggest designing for spacing. Like in the example above, I'd use a setback of 6' 11 1/4" to the face of the hip girder. The flat top of the girder would be 12' 1 1/2". That way all the end jacks would be 2' O.C. all the way across.

We drop the flat TC of all the stepdown trusses, and build a gable frame to lay in there. In this case it could be done with 2X4s laid flat up the rake.

If any of that doesn't make sense I can try to draw something up tomorrow.