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Construction: Open Web Wood Truss Dropped on Ledger?

Construction: Open Web Wood Truss Dropped on Ledger?

Construction: Open Web Wood Truss Dropped on Ledger?

(OP)
1st Post. Wrestling with a residential construction open web truss connection detail. I am NOT an engineer but a designer (residential). Find myself here quite a bit so figured I'd join up. I'll end up needing a structural engineer for this job but trying to get my head wrapped around a decent solution that I can present him with.

House I'm designing has a basement and I'm trying to keep finish floor at 1st floor ground level as low as possible. Since code requires clearances to wood framing members to be x distance this requires that I drop my open web wood floor trusses so that top chord is as close to the top of the cast-in-place basement wall as possible.... ideally at the same elevation as the PT Sill plate anchor bolted to the top of the basement wall in a typical bottom chord bearing condition.

Some ways that I can come up with to do this would be
1. Cast in a 4" deep shelf (Would give 3-1/2" bearing & 1/2" space required) at the top of the 10" CIP concrete wall either the full depth of the truss or something less (say double top chord depth) and just have the rest of the truss dropped below the shelf whatever distance required.
2. Anchor bolt a ledger board to the wall and attach trusses to that with hangers.
3. Attach truss hangers directly to the CIP concrete wall
4. Hang truss hangers from on top of the plate
5. Hang truss hangers from top of CIP concrete wall

With all the hangers, concerned about rust/ condensation
With the wood ledger concerned about moisture migration even with a vapor barrier between it and the CIP concrete
With not having the truss actually under the stud wall (in any of these conditions), concerned about how the detail works where the sub flooring "spans" the gap from the top of the truss to the top of the sill plate.... and getting this all lined up.

Anything I'm overlooking that can cause me/ my client problems with this down the road or during construction?

Looking to design in as much flexibility as possible but don't want to add unnecessary expense.

Any ideas/opinions as to the best way to approach this?

RE: Construction: Open Web Wood Truss Dropped on Ledger?

(OP)
... Another option would be to have a separate load bearing stud wall supporting the trusses and not involve the CIP wall at all. Seems odd to me somehow however.

RE: Construction: Open Web Wood Truss Dropped on Ledger?

I'd do option 1, you can provide some horizontal and vertical reinforcing in the up-turn portion of the foundation wall. The depth of the shelf could probably be closer to your floor joist depth, just make sure the contractor installs a sill and anchor bolts, this will provide lateral support for the wall. From a constructability standpoint, this would be easy for the contractor to block out in the formwork.

RE: Construction: Open Web Wood Truss Dropped on Ledger?

What about top chord bearing trusses? The bearing depth is only 3"

RE: Construction: Open Web Wood Truss Dropped on Ledger?

(OP)
Thanks guys for the quick responses!
Shotzie- It could work. My biggest concern with this is getting the shelf as dead level as possible.... since I'll need to align top of truss with top of sill plate. Guess that individual trusses can be shimmed without any structural issues? Material? Design in a shim requirement for leveling purposes? Only other real concern is that I may need the full 10" at locations where I will have posts bearing on the basement foundation wall... another topic to follow.

XR250- I beat that detail to death prior to barking down this avenue. If I'm understanding you correctly, The "problem is that I'll still need the sill plate to have top chord bearing condition. So end up with double top chord bearing depth (3" you're talking about as well correct?) plus the 1-1/2" for the sill plate. So, after all said and done I end up 3" higher than in the other "solutions" I've bringing up. As an aside, I'm also going to have some patios poured directly up against the basement foundation so having another 3" of wood "exposed" up against the poured patio that needs to be contended with with flahsing, makes it less appealing to me. Certainly is the simplest solution and I may need to fall back on it yet. I know it's only "3" difference but I'll end up needing another tread if I add it in..... I'll spare you the details.... complicated site and a huge wish list.

Shotzie/xr250- Would you say that the detail shotzie is describing would be considered a reasonably "common" detail.... at least nothing that my contractor is not going to point fingers at? If so, any idea how the floor sheathing transition from top of truss to top of sill plate works out and where I'm looking for problems here?

RE: Construction: Open Web Wood Truss Dropped on Ledger?

Here's a detail I have used successfully numerous times.

RE: Construction: Open Web Wood Truss Dropped on Ledger?

(OP)
bhiggins- PERFECT! Gives me a lot more clarity as to direction. Thanks a bunch for taking a look at my post and sharing your detail.

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