architect wants a scissor hip roof truss system. Room size is 22x 34...where to put girder?

[fatfretter]

WHere to put girder trusses? SHOuld be simple right? Cheaper than conventional framing.? Rof is very steep ...around 15" rise per foot...interior slope maybe half of that.
Thanks

 

[ztengguy]

not sure I follow. wouldnt the trusses be the support on each wall? why a girder truss?

 

[BAretired]

Put one girder truss at each end of the ridge.

BA

 

[dik]

I would think that you would have scissor trusses between the intersecting points of the hip rafters with a girder truss at the intersection and that you would have triangular trusses to 'fake a cathedral ceiling'. On the 34' dimension, the first girder truss would be at 11' approx and the second would be at 23' with scissor trusses framing between the 11' and 23'. You may have secondary girder trusses going from the corners to the mid span of the girder truss and have regular small trusses framing in the corners. I'll try to do up a sketch.

Dik

 

[hokie66]

Hipped roof systems normally have the girder trusses downhill of the end of the ridge. Does the ceiling slope up from the ends as well as from the long sides?

 

[dik]

Something like the sketch...

 

[msquared48]

Here, for a double hip truss system, the Hipmaster, or girder truss is normally situated 8 feet from the outside wall that the hips span to.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[woodman88]

I agree with msquared48, a 8' setback is commonly done. It is more cost effective. In your situation a 9' setback may also work out. As there from be no need for a 10' setback common scissor truss.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[dik]

The 8' setback is often used (almost standard) with a hip roof, but, with a flat ceiling. The proposed scissor truss does not lend itself to that configuration.

Dik

 

[msquared48]

I understand.

Might want to consider glulam hips framing to the girder truss BA described with 2x rafters stick framed to it.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[fatfretter]

Wow...I didnt expect all the responses. Thanks everyone! Here are two drawing IM working on. I think the scissor trusses wil save money over conventionally framing the sapace. I also want a hight flat clg below the bottom chord of the scissor truss.It could probably be incorporated into the scissor truss..I think, of just framed on afterwards.I set the girder trusses back 8 feet from the outside face of the stud walls. Hope I can load these two sketches.

 

[fatfretter]

Here is the second sketch......

 

[fatfretter]

Try again to post frmg plan

 

[msquared48]

Second sketch didn't load properly...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[fatfretter]

I will try once more, sorry

 

[hokie66]

Looks good. That's the right place for the girder truss. Flat bottom section and flat top section.

 

[fatfretter]

Hokie, They are scissor trusses though,, but maybe with a flat clg or section on the bottom chord. But all the bottom chords are sloping, but may inforporate a flat section ......

 

[woodman88]

With the truss spans you are talking about there is no problem doing this with a 6' to 11' setback. With or without the flat ceiling. The most economical with the flat ceiling IMHO would be a hip girder setback to the flat ceiling.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[fatfretter]

woodman,
When you say hip girder set back to the line of the flat ceiling....and maybe that point is where the girder scissor truss is located that carries the mono-scissor trusses at the short end? That might work but will have to look at the clg height I want, but that will probably work.
Thanks

 

[azcats]

Is there any problem with transportation of these 14' x 22' trusses?