Wood trusses on wood studs
Wood trusses on wood studs
(OP)
I have a 50'x80' single story structure. Roof framing is pre-fab gable wood trusses spanning the 50' direction and I would like to space the trusses @ 24" oc. The question I have is about stud spacing for the load bearing walls. Ideally I would like to space the studs @ 12" oc topped with a double 2x bearing plate. Each truss is to be lined up with a stud in the wall.
What this means that every other stud of the wall would be support a truss. Is a single stud a good/acceptable practice for supporting roof trusses? Should the studs be double at bearing locations?
Studs are 14' feet tall and the peak of the truss is 14' (28' building height).






RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
If you canb get the vertical and lateral to work with double 2X8 studs considering live load deflection at L/360 for any sheetrock, the contractor will love you, but probably not the Architect. Then you nay have to go to three or four 2X6's under each truss.
Some plywood shear wall options in the IBC can be applied over studs at 24" on center.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Wood trusses on wood studs
But now I have a question about IBC table 2306.4.1. Foot note f talks about 3" nominal member and it is not clear to me if it could be double 2x8s?
RE: Wood trusses on wood studs
I would consider using 3.125 X 7.5" glulams, or even 5.125 X 7.5 if needed here. Some Architects like the wood look if it is at a window wall where you would not have to sheetrock over the multiple 2X8 or 3X minimum member. Otherwise use 4X members, as 3X may be hard to get in some locations. Then there is no question with the plans checker.
Interestiong to note that you must be usong IBC 2006, because that table is 2306.3 in the 2009 IBC. Note f is unchanged.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
2/ 90x45mm as the Top plates.
90x35 mm studs @ 450mm centres. This is fine for gravity loads, wind uplift loads, and wind pressures inward/outward.
Nogging between studs at mid height for a standard 2700-3000mm high wall.
Trusses can sit ANYWHERE on the top plates. They are designed to span the 450mm for gravity loads, and the tie down spacing for wind uplift loads.
We only ever line up studs/jamb studs (packed) under bigger Girder trusses that carry a lot of load.
Hope this helps. This is Standard and is used on the majority of houses. Many also just use 70mm wide studs, if they want to cheap out.
RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
For high wall homes, or those with stair voids to an external wall, we often use closer spaced packed high studs.
RE: Wood trusses on wood studs
Actually 2x8 studs @ 16" oc do work but I wanted to line up the trusses (spaced @24") with a stud. I guess what you are suggesting is that the trusses don't necessarily need to line up with studs @ each and every location and that the top plate could be used to span between studs as required. My truss reaction is about 2.6 k (25psf D, 25 psf L plus a 350# point load at some locations) and based on that (2)2x8 top plates would fail for worst case ie truss right between two studs. So I feel that I do have to line up my trusses with studs.
Typical wind load is 20 psf
FYI-I have done 3 project with wood trusses but they all used masonry bearing walls. This is first one with stud bearing wall, thus the curiosity. Thanks for all the info.
RE: Wood trusses on wood studs
RE: Wood trusses on wood studs
EIT
www.HowToEngineer.com
RE: Wood trusses on wood studs
With 12" stud spacing, there is essentially no load sharing among studs. The aligned stud carries nearly all of the truss reaction while the other carries essentially no vertical load at all.
Double studs at 24" o/c is another option but may be problematic for drywall.
BA
RE: Wood trusses on wood studs
I guess its hard for me to give advice given the difference in standard practice and costs of components etc.
Here our tradesmen are quite expensive and lazy, getting them to line the trusses up with studs is not economical, and they'd not take kindly to the idea of it either! (at least for residential).