2x4 Double Top Plate Capacity
2x4 Double Top Plate Capacity
(OP)
How are you guys calculating for the point load capacity of a double 2x4 top plate? Are you taking into account any composite action between the two members with the limited amount of code nailing or just basing it on twice the flatwise bending properties of a 2x4?






RE: 2x4 Double Top Plate Capacity
RE: 2x4 Double Top Plate Capacity
Mike McCann, PE, SE (WA)
RE: 2x4 Double Top Plate Capacity
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.
RE: 2x4 Double Top Plate Capacity
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.
RE: 2x4 Double Top Plate Capacity
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.
RE: 2x4 Double Top Plate Capacity
RE: 2x4 Double Top Plate Capacity
Mike McCann, PE, SE (WA)
RE: 2x4 Double Top Plate Capacity
Just had a contractor rip the 16 ft. flat roof off a house and install 60 ft. clear span, (yes 60 ft.) 24" o.c. roof trusses on 16" o.c. walls. I think he will have a top plate problem.
RE: 2x4 Double Top Plate Capacity
DaveAtkins
RE: 2x4 Double Top Plate Capacity
If you think too hard about this your head will explode. Specifically - load transfer from floor to floor, and point loads under trusses / joists.
I use southern pine #1 top plates and limit stud spacing to 16" o.c. I specify cripples over studs so that the wall loads from upper floors transfer through to the studs, not the top plates. Using this you should be good for most cases unless you have a wall picking up long spans on each side.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: 2x4 Double Top Plate Capacity
DaveAtkins
RE: 2x4 Double Top Plate Capacity
I could see this becoming an issue though if there is an interior load bearing partition with long spans on each side and the floor joist is in a multi span situation versus simple span.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: 2x4 Double Top Plate Capacity
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.
RE: 2x4 Double Top Plate Capacity
We can't even get SYP 2x4's here unless they are pressure treated. (central NC)
RE: 2x4 Double Top Plate Capacity
Thank you for your time
Bill Lindau
RE: 2x4 Double Top Plate Capacity
RE: 2x4 Double Top Plate Capacity
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.
RE: 2x4 Double Top Plate Capacity
Mike McCann, PE, SE (WA)
RE: 2x4 Double Top Plate Capacity
But this is only true if the bottom of the ribbon board is in contact with the top of the double sill plate, correct? In which case, it's usually just full depth rim board.
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.
RE: 2x4 Double Top Plate Capacity
Mike McCann, PE, SE (WA)
RE: 2x4 Double Top Plate Capacity
And now its my fault?
Bill
RE: 2x4 Double Top Plate Capacity
Mike McCann, PE, SE (WA)
RE: 2x4 Double Top Plate Capacity
Bill
RE: 2x4 Double Top Plate Capacity
RE: 2x4 Double Top Plate Capacity
The only issue that I have ever seen related to this was with 30' trusses in a clubhouse supporting heavy DL and 100 psf LL. The plates crushed slightly, but did not fail.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: 2x4 Double Top Plate Capacity
A single upper ribbon results in the accumulative load being placed on the top plate of the wall below, potentially at locations where there is no stud. Thus resulting in the bending of the upper plate.
If the ribbon is stiff enough it may transfer the accumulative load to the trusses with studs directly below them. this may overload those studs
RE: 2x4 Double Top Plate Capacity
RE: 2x4 Double Top Plate Capacity
RE: 2x4 Double Top Plate Capacity
I have been privy to 2 schools of thought at 2 different companies:
*Align the trusses with the studs. Studs at 12", trusses at 24". Add blocking between trusses (over studs)
or
*Trusses at 19.2" studs at 16" o.c. Add blocking over studs. SP plates
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller