When building partition walls whicher are longer than a 2x4's length, how should butt joints in the top plate be handled?

I can think of 2 methods off hand: two methods of partition wall top plate butt joints

Assuming these are acceptable methods then I have some extra questions:

  • Option A: Does the break need the occur not only on a stud, but with either a rafter, floor joist, or blocking above the joint as well?
  • Option B: Should 16" on center be maintained for the whole length of the wall, meaning only out of those two studs is actually 16OC?

Option A is acceptable for exterior walls and bearing walls, assuming a second top plate is installed correctly....lapped a minimum of 24” (See ICC R602.3.2.) and nailed properly. BTW, the top plate splice need not occur at a stud. (Nailing is complicated...it depends a lot on what seismic zone you’re in.)

Option B is allowed, but splicing (nailing) of studs together is important...and yes, it’s critical to keep your 16” or 24” wall stud spacing consistent, because the wall sheathing and interior gypsum board is laid out to those dimensions.

Oh, with regard to distance of rafters and trusses to studs, yes, they need to occur within 5” of a stud.

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  • Is option A, without a second top plate, acceptable for a non-load bearing interior wall? – Jay Sep 16 '18 at 16:15
  • No second top plate is required for non-load bearing walls. However, from a practical standpoint, it makes the wall stiffer and allows a good connection at intersecting walls. – Lee Sam Sep 16 '18 at 16:28
  • In the case of not using a 2nd top plate in option A would it be important that the joint line up not only on a stud, but also on a rafter/block/joist or would it be sufficient to just have it lined up on a stud like the picture? – Jay Sep 16 '18 at 16:44
  • Yes, it just needs to align with a stud...because it’s non-load bearing, right? (There is a way to use a single top plate in a bearing wall, but it’s complicated and requires a strap.) – Lee Sam Sep 16 '18 at 20:05

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