Stud alignment in mid-rise wood buildings 2

[mike20793]

How do other engineers handle stud alignment with floor trusses/joists in 3-5 story wood buildings? Since most of my wood buildings use floor trusses and the truss manufacturers typically use 2x4 ribbon boards, I usually spec that the studs must align with trusses and so forth throughout the wall stacks. The double top plate can usually span between studs for one floor load, but any more than one floor, they don't theoretically work. Any thoughts? I'd really be interested in hearing from any west coast engineers since apparently this doesn't seem to be too much of an issue with TJI joists they like to use out west.

 

[RFreund]

Making them align all the way up in tilt up wood walls requires thinking about truss locations ahead of time and that's something framers are not good at

- right, right, I see now. Thank you. We have been aligning them, I just didn't realize it was an becoming an issue.

EIT

http://www.HowToEngineer.com

 

[XR250]

Yes, if you look at the installation requirements of the rim board, it requires nailing through the rim board into the ends of the trusses or joists. Easy to do for one wall, but hard for the other. There's also an issue with the attachment if you're using the rim board in a shear wall to transfer loads.

You could you shear transfer clips from the rim board to the top plate. You could also use clips to attach the rim board to the trusses.
Does the rim board need to be fastened to the trusses for buckling resistance? If so, switch to an LVL.

 

[mike20793]

Any input from any Canadian brethren?

 

[jayrod12]

I've never had any real arguments from contractors regarding this. We put the note on our drawing that all studs must align floor to floor. I also include an additional note that all point loads and mis-aligned studs must be continuously blocked down to the foundation.

So most contractors that have asked the question have received this response from me "You can align the studs as per note 188 on the plans or provide continuous blocking below all the mis-aligned studs as per note 189 on the plans. The choice is ultimately yours however from an economics standpoint I advise you adhere to note 188."

They've never called about it again. And oddly enough, continue to call the company for further projects so I must not be that difficult to deal with.

 

[KootK]

In my market:

1) mostly TJI
2) lots of pushback on stud alignment for non-panelized walls.
3) no robust solution to this problem.


I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Brad805]

Aligning the studs is not all that practical except for the demising walls. It may happen in other wall lines if the crew chief prepares good sketches, but that takes someone that pays attention to details. I know some have said they have not encountered problems, but unless you checked carefully I have my doubts. In our case most prefer to use blocking. Proper shop drawings for bearing lines would solve this problem, but that will not happen anytime soon in the wood industry.

Letting in headers is time consuming and may not solve the problem you think it does until the floor deforms. I would expect a 1/16" fit tolerance for typical carpenters. If you consider that and the differences between cross grain vs. lengthwise shrinkage I would expect a small gap between the header and top plate a few months after the building heat is turned on. If they are cutting the notches with a typical skil saw you may end up with one or two small circular slits extending past the inside notch corners.

Like Koot, we mostly use TJI's. Many like to use an extra bottom plate for screeding the sound barrier topping so we have been using Simpson SDS screws of late to attach walls to the rim boards. We do not like the extra plate, but it is practical, and you all know the wood market.

 

[RFreund]

Why does TJI change things?

EIT

http://www.HowToEngineer.com

 

[XR250]

I am not sure why aligning things thru the stories is such an issue. Most framers that I work with alway pull off the same corner or wall for the floors and roof so things naturally align. Seems to make their jobs easier.