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Stud Location?
- Thread starter SteelPE
- Start date
- Thread starter
- #3
Thank you.
I understand about designing the top plate for bending. Last time I looked into that it failed miserably.
When I was framing houses during college summer vacation I was told to always locate the joist/studs directly above the joists below. This required a little more planning but was a much better system.
I understand about designing the top plate for bending. Last time I looked into that it failed miserably.
When I was framing houses during college summer vacation I was told to always locate the joist/studs directly above the joists below. This required a little more planning but was a much better system.
MiketheEngineer
Structural
Nope - usual double top plate has traditionally handled the problem.
Might not be able to prove that - but it has worked for 100 years.
Might not be able to prove that - but it has worked for 100 years.
- Thread starter
- #6
BA
I understand the check.
I was talking to a contractor I am currently doing a project for and he commented about my 2’-0” o.c. stud spacing. I stated that the 2’ spacing was in order to make the studs fall in line with the roof trussed above. In this particular case 2’-0” o.c. didn’t work for the loads so I have to reduce the spacing to 1’-0” (the contractor didn’t want to use a large knee wall to reduce the height of the studs). The contractor suggested using 16” stud spacing. Once I informed him of my requirement he stated the typical “never done that before” and “the building inspector has never complained”. I was just wondering if there was a code requirement that I couldn’t find requiring this spacing…. otherwise when using the prescriptive IRC he is correct (in this case we are outside of the prescriptive code).
He is going to use the 1’-0” spacing.
I understand the check.
I was talking to a contractor I am currently doing a project for and he commented about my 2’-0” o.c. stud spacing. I stated that the 2’ spacing was in order to make the studs fall in line with the roof trussed above. In this particular case 2’-0” o.c. didn’t work for the loads so I have to reduce the spacing to 1’-0” (the contractor didn’t want to use a large knee wall to reduce the height of the studs). The contractor suggested using 16” stud spacing. Once I informed him of my requirement he stated the typical “never done that before” and “the building inspector has never complained”. I was just wondering if there was a code requirement that I couldn’t find requiring this spacing…. otherwise when using the prescriptive IRC he is correct (in this case we are outside of the prescriptive code).
He is going to use the 1’-0” spacing.
SteelIPE,
I have had the same problem a few times. On one occasion, the architect wanted a 16" spacing for drywall support. The roof trusses were spaced at 2' centers and the double plate did not satisfy the code, so I specified a triple top plate. I didn't feel that it added significantly to the cost.
The architect took exception to this and sought the opinion of another engineer who argued that the double top plate was adequate based on his experience. So they went with a double top plate and I lost the job (I wasn't sorry).
If you use a 1'-0" stud spacing, it seems to me that the studs will share wind load equally, but alternate studs will feel little or no axial load from the roof. If you used double studs at 24" centers, all studs would be loaded similarly.
BA
I have had the same problem a few times. On one occasion, the architect wanted a 16" spacing for drywall support. The roof trusses were spaced at 2' centers and the double plate did not satisfy the code, so I specified a triple top plate. I didn't feel that it added significantly to the cost.
The architect took exception to this and sought the opinion of another engineer who argued that the double top plate was adequate based on his experience. So they went with a double top plate and I lost the job (I wasn't sorry).
If you use a 1'-0" stud spacing, it seems to me that the studs will share wind load equally, but alternate studs will feel little or no axial load from the roof. If you used double studs at 24" centers, all studs would be loaded similarly.
BA
msquared48
Structural
Remember though that it's not just the double top plate that resists the vertical load, but the plywood sheathing, and even the sheetrock, help stiffen the plate and decrease the effective span. I cannot put that to numbers, but the effect is still there.
Mike McCann
MMC Engineering
Mike McCann
MMC Engineering
- Thread starter
- #10
Msquared48
This at is my problem. What is the capacity of the sheathing to support some of the load? If I can’t justify it by numbers, I’m not going to put in on the design documents.
Also, the daughter of this contractor is a lawyer. Not going to mess with that.
This at is my problem. What is the capacity of the sheathing to support some of the load? If I can’t justify it by numbers, I’m not going to put in on the design documents.
Also, the daughter of this contractor is a lawyer. Not going to mess with that.
Another treatment which I considered but didn't use was to ensure that the studs and trusses aligned at four foot centers, then use a couple of 2 x 6 under the top plate where the truss was half way between studs. Could work but would need joist hangers to get a decent connection. Maybe in my next lifetime. I'll let you guys worry about it for now.
BA
BA
- Thread starter
- #14
I had a similar problem last year with a 60' wide strip mall (16" truss spacing, top chord bearing low slope open web wood trusses spanning 30' with steel post-beam at mid-width) with a contractor wanting to change the studs to 24” spacing. My position was a stud was needed due to continuous load path, uplift, etc. A local code official was asked to referee and said a stud wasn't needed citing IBC 2006 section 2308.9 "Conventional Light-Frame Construction". There are limitations listed in section 2308.2 and one is stud height. My project stud height varied between 15' & 16' so I said 2308 didn't apply plus they didn't address uplift and lateral load path. I'm pretty sure it got built the way the contractor wanted it. Section 2308 is intended for typical mainstream projects so an engineer isn’t needed. That’s fine as long as its meets the limitations of section 2308.2. Check the IBC commentary to chapter 23.
I agree with msquared48 and BAretired both. Based on experience a double top plate works particularly in you have plywood sheathing on the outside. However like others above I have specified triple plates before.
On the jobs I worked on sheet rock was used on both sides of the studs. On jobs that I signed, when I could not get the numbers to check, I would use triple plates or other methods to distribute the load.
Another approach that has been used is to space the studs at 16" o.c., adding one additonal stud at 2' directly under the trusses.
Regarding Conventional Framing, I am not as familair with it now, as I was in the past. However I would expect that when trusses are used Conventional Framing doesn't apply.
As pointed out by Smb4050 when CF is used you must have framing that complies with the CF provisions of the code. CF in the past, gave stud size, height and spacing for walls that supported floors and roofs framed with joists. The load on the walls was limited by the maxium spans allowed for floor and roof joists. A 2x10 spanning 16' is very different than floor trusses spaning 30'.
On the jobs I worked on sheet rock was used on both sides of the studs. On jobs that I signed, when I could not get the numbers to check, I would use triple plates or other methods to distribute the load.
Another approach that has been used is to space the studs at 16" o.c., adding one additonal stud at 2' directly under the trusses.
Regarding Conventional Framing, I am not as familair with it now, as I was in the past. However I would expect that when trusses are used Conventional Framing doesn't apply.
As pointed out by Smb4050 when CF is used you must have framing that complies with the CF provisions of the code. CF in the past, gave stud size, height and spacing for walls that supported floors and roofs framed with joists. The load on the walls was limited by the maxium spans allowed for floor and roof joists. A 2x10 spanning 16' is very different than floor trusses spaning 30'.
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