Stud size

[StephenGreene]

Full two-story house. Twelve foot ceilings on first floor and ten foot ceilings on second. Living area full two-story height (23'-7") with two exterior load-bearing walls (roof). Best I can tell, code says you can go full 20' with 2x6 framing. What is code for 23'-7" exterior load-bearing walls? 2x8? or 2x6 @ 12"O.C.?

 

 

Thanks.

 

[Bob-Roraback]

https://up.codes/viewer/arkansas/irc-2021/chapter/6/wall-construction#R602.3

[StephenGreene]

1 hour ago, Bob-Roraback said:

https://up.codes/viewer/arkansas/irc-2021/chapter/6/wall-construction#R602.3

 

 

Thanks, but I don't see where that answers my question.

[rgardner]

4 hours ago, StephenGreene said:

 

 

Thanks, but I don't see where that answers my question.

If it’s not in the table then it can’t be prescriptive framing.  Which means you need an engineer to design and seal the design to use those heights.  Most likely they will design with an LSL stud or similar.

[Kbird1]

20 minutes ago, rgardner said:

If it’s not in the table then it can’t be prescriptive framing.  Which means you need an engineer to design and seal the design to use those heights.  Most likely they will design with an LSL stud or similar.

 

My thinking is the same  ie LSL Studs.... maybe even 2x8 ?

 

* I am not an Eng.  

 

M.

[StephenGreene]

Thanks, Ryan. I suspected as much but wasn't sure.

[Joe_Carrick]

From a structural standpoint it will depend on blocking and shreathing to mitigate the potential buckling as well as the compressive stresses.  It's unlikely that the compressive stress is going to be a problem even for 2x6's but buckling in either or both axis may be a problem.  

 

Assuming these walls are balloon framed :

• unblocked & sheathed only one side --- use 3x8's @16" o.c
• unblocked & sheathed both sides --- use 2x8s @ 16" o.c.
• blocked at mid height & sheathed both sides --- use 2x6s @ 16" o.c.

If Platform framed (2x6 plates & box floor joists) at 2nd floor line:

• 2x6's at 16" o.c are sufficient.

 

I ran this thru my structural program for the above.

 

Note that it might be very difficult to obtain any of these sizes in 24 ft lengths, not to mention the difficult of raising a wall of that height.  I would platform frame for those reasons.

 

[rgardner]

5 hours ago, Joe_Carrick said:

would platform frame for those reasons.

Doesn’t pass code in MANY AHJs.

[StephenGreene]

17 hours ago, Joe_Carrick said:

From a structural standpoint it will depend on blocking and shreathing to mitigate the potential buckling as well as the compressive stresses.  It's unlikely that the compressive stress is going to be a problem even for 2x6's but buckling in either or both axis may be a problem.  

 

Assuming these walls are balloon framed :

• unblocked & sheathed only one side --- use 3x8's @16" o.c
• unblocked & sheathed both sides --- use 2x8s @ 16" o.c.
• blocked at mid height & sheathed both sides --- use 2x6s @ 16" o.c.

If Platform framed (2x6 plates & box floor joists) at 2nd floor line:

• 2x6's at 16" o.c are sufficient.

 

I ran this thru my structural program for the above.

 

Note that it might be very difficult to obtain any of these sizes in 24 ft lengths, not to mention the difficult of raising a wall of that height.  I would platform frame for those reasons.

 

Thanks, Joe. 24' fir and/or LSL is not hard to get around here, though it is expensive. but yeah, framing that would not be easy.  scaffolds or SkyTrak would be the way.

[Gr8trim4u]

Take a look at bc calc.  It has a wall designer section.  My go to for getting thr structural elements. I have an enginner review prior to submissions.