Parapet wall to truss connection 1

[struct_eeyore]

I've got a condition where I have to terminate flat roof wood trusses into a face of a parapeting (can I say that?) wall.
The bonus here is that the roof slopes, so in order to keep the sheathing flush with the top chords, I'm showing the trusses installed on an incline.
I've been mulling over the connection details and have come up with something like this (below)
Wondering if anyone will see any issue with what I'm proposing here - or any other comments/suggestions.
Thanks in advance.

 

[Eng16080]

Or you could use a steel angle with one or two wood nailers on top.

 

[struct_eeyore]

@Eng16080 - Good catch on the 5" spacing, an embarrassment on my part. I'm gonna sleep on the wood frame parapet idea. Do you notch your roof diaphragm around the parapet extensions (when sistered to trusses)? The carpenters/roofers here are just a step up from unskilled laborers, so I'd be concerned about the execution of a detail like that.

@pham - I think your explanation is sufficient to put this to rest - unless anyone else takes issue.

 

[Eng16080]

Good catch on the 5" spacing, an embarrassment on my part

That's probably being a bit hard on yourself!

Do you notch your roof diaphragm around the parapet extensions (when sistered to trusses)?

I would probably try to avoid the notching. I might try to do something like this:

I would try to justify the diaphragm load transferring from the sheathing into the truss, to the ribbon board, to the wall sheathing, and to the wood sill plate. The truss should have some capacity in weak axis bending to span a short distance without any sheathing. If that doesn't work or seems sketchy, you could:

1. Add diagonal bridging between the trusses.
2. Add strongbacks to the trusses to increase weak axis bending capacity
3. Use a flat 2x10 or similar directly below the roof sheathing and between the trusses, with nailing into it from both the roof sheathing and wall sheathing.
4. If the parapet will be fully sheathed in a structural material including along the inside, you could use that to your advantage.

It may well be a pain detailing the parapet with wood (usually is), but due to the concerns mentioned by Ron, I would avoid having trusses spanning inside to inside of cmu.

 

[Celt83]

I’ve never been a fan of the two-ply ledger but I see it used all the time.

If the parapet doesn’t need to be masonry we have had a lot of truss suppliers in our region prefer to build the parapet into the end of their roof trusses, have been told the limit for that is about 5-6ft tall parapets.

If the masonry has to stay for rating or other reasons then I’d suggest keeping the trusses flat and doing either a steel angle ledger or solid treated psl ledger. There is also the option of doing directly attached masonry hangers but if doing something like that may want to bring up tighter tolerance requirements.

I am not a fan of skewing the trusses to create the slope think you’d need stability bracing throughout the roof to limit the roll out. Would prefer flat trusses and sloped insulation.