Exterior non load bearing wall bracing in wood construction

[MMett]

I have designed several multi-story wood buildings using a typical detail for bracing the top of the exterior non load bearing walls (parallel to the floor trusses). The non load bearing walls are always built to the same elevation as the load bearing walls, then two rim joist are placed on top of the wall to get up to the floor deck elevation, creating a hinge at the top of the stud wall / bottom of the rim joists. The floor decking is then nailed to the top of the rim joists and the wall above is built on top of the floor decking. The detail I have shown calls for braces at 32" o.c. from the top of the non load bearing wall up to the floor deck at about a 45 deg angle. I have recently found out that the brace is rarely, if ever, installed because of interference with nearby floor trusses. I would like to specify a different detail that can be installed without making the connection too cumbersome. I cannot find any typical details for this condition. I spoke with one framer who suggested that the ceiling gyp board would resist any lateral loads. I'm not comfortable using gyp board for shear transfer if I don't have to because drywallers rarely see a set of structural drawings to notice a special nailing/screwing requirement. Also, what if we have a lay-in ceiling. The size of several rooms prevents the use of "cross walls" teeing into the exterior wall to brace it. It some locations those walls are over 18' apart. Am I not finding any details to prevent or reinforce this hinge because it only exists on paper, but not in the field? Anybody have any suggestions?

 

[UcfSE]

Try framing the NLB walls to the underside of the sheathing.

 

[MMett]

I have considered building the non load bearing walls up to the floor decking, but (a) the framers don't like it because the precut studs on the job would then be two different lengths (b) the top plates would not be continuous at the intersection of the load bearing and non load bearing studs.

 

[rgerk]

I have used solid blocking perpendicular to the NLB wall in the past. Try using blocking made from the rim joists.

For instance, if your floor joists/trusses are 12" tall, the rim board will be 12" tall. Blocking, using 12" tall rim board, at around 32" to 48" perpendicular to the NLB wall and joists should provide plenty of lateral resistance. If you are using floor trusses that exceed typical rim board sizes, have the floor truss manufacturer design a blocking truss to brace the walls.