Truss bearing on shear wall

[JStructsteel]

Since im on a roll here, whats the better detail for a truss bearing on a shear wall? Got a high-low roof, lower trusses frame into shear wall. To keep shear wall continuous, I was going to provide ledger board w/ truss hanger. My second thought is split the wall, double top plate for truss bearing, then wall on top of truss to high roof. This seems alot of work, plus the side i have sheathing would be in the truss.

Here is my preferred detail:

 

[JStructsteel]

That picture sucks. Here is a pdf

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1709394124/tips/high-low_shear_wall_bddyaa.pdf[/url]

 

[milkshakelake]

Presumably, you've considered lateral load on that stud, if any. Your detail works. The essence of platform framing is to finish the walls and then the joists/trusses. If you split it up with a double top plate, it slows everything down to a crawl. The upper roof can't be constructed until the lower roof is done. You'd also need a really tall rim joist. And you get a little bit more shrinkage.

 

[Eng16080]

I often use a similar detail. These are the important things I would typically check in finalizing the detail:
[ol 1]
[li]Design the truss to bottom ledger and bottom ledger to wall (typically screws into each wall stud) connections to resist the vertical load from the truss. If there's a diaphragm shear force at the ceiling level, design these connections for that lateral force as well.[/li]
[li]Design the top ledger to wall connection to resist the lateral load from the roof diaphragm and possibly also a vertical force (depending on how the truss is designed). I usually include a note specifying the roof sheathing nailing to the ledger (which typically is the same as the diaphragm edge nailing).[/li]
[li]If the lower roof diaphragm is designed as a cantilever, as could be the case if there isn't any lateral support to the right of the lower roof, then there will be compression and tension forces pushing the lower roof into and pulling it away from the wall. In that case, additional detailing is probably needed to resist the tension force (similar to a deck tie-down connection).[/li]
[li]Although it's not specifically a structural concern, I'll often show fire blocking between adjacent wall studs at the ceiling level and possibly at the roof level as well.[/li]
[/ol]

One more thing: for the ledger to wall connections, I'll note that the ledger must be fastened (usually with wood screws) into the center of each intersecting wall stud. Without that note, I think there's the risk of the contractor only fastening the ledger into the sheathing.

 

[XR250]

One more thing: for the ledger to wall connections, I'll note that the ledger must be fastened (usually with wood screws) into the center of each intersecting wall stud. Without that note, I think there's the risk of the contractor only fastening the ledger into the sheathing.

The risk is likely the same with or without the note
Also, do you give an off-center tolerance?
I usually call it out in the center but make sure my connection has twice as many screws as needed.

 

[Eng16080]

The risk is likely the same with or without the note

I think the risk is a little lower with the note, you know, that's assuming they actually have the (correct) plans at the job site and are using them! It's a good point, though, and perhaps a downside of using this detail.

Also, do you give an off-center tolerance?

No. As long as the fastener doesn't miss or come through the side of the stud, I'm not too concerned with it being exactly centered.

I usually call it out in the center but make sure my connection has twice as many screws as needed.

I try to add extra fasteners if possible.

 

[Celt83]

I’ve done the ledger to stud detail once and it was a nightmare. Simpson SDS screws have zero tolerance in this application and must be installed dead center, the framers ended up splitting almost every stud they screwed into (we had notes to pre drill and soap to try and limit the splitting potential but was still problematic)

Lately if the loading is significant will do 2x12 blocking between studs with jack studs under each end and fasten a ledger to the blocking. For light loads look at letting in the ledger.

 

[Eng16080]

Celt83: Well, I'm starting to 2nd guess my detail now. Hopefully your situation was just a case of a bad contractor and not the norm.

 

[JAE]

Why don't you simply extend the truss over the wall and have a vertical truss end strut extending upward to the upper roof?
The truss manufacturers can do this easily and it removes any issues with a ledger and also removes eccentricity on your stud wall below.

This assumes, of course, that the upper roof, and the lower roof diaphragms are separately stable from lateral movement left-right on this image.

I might add that we do this all the time with flat-chord truss parapet walls.