alternate for ledger and elevated slab

[bdruehl]

several contractors have expressed distaste for my standard detail for elevated slab joist attachment to a ledger with the tension straps and the bolts, etc... admittingly, it does appear to be a pain in the rear

i am exploring an alternative: 'notching' the foundation stemwall or retaining wall (perpindular joists) for the joists to seat into and rest on in bearing. what would be considered good connection standards and notch depth (2" seems too small), stemwall width, tension straps - or just bolts and a23/a35 clips to a sill plate, or maybe no sill plate since i am using P.T. 2x12...???

 

[jheidt2543]

IMHO your details should have two goals, satisfy the structural requirements and be cost effective. A detail that is too costly compared to other alternatives might be safe, but it isn't good engineering.

You have stated that your details are "a pain in the rear", so ask the contractors what they would suggest for a more cost effective detail that accomplishes the same structural intent. You are not asking them to design the detail, only provide construction input.

Maybe I'm not understanding your detail, but why won't joist hangers on a ledger work?

 

[bdruehl]

Joist hangers (2x12 @12" o.c. spanning 10-12 feet max) on a ledger (joists running parallel to car path) do work but it seems that the amount of bolts for the ledger shear under car loads and the tension straps (like simpson ltt19) would be cumbersome to install. I come up with 3/4" bots at 12" o.c. in a 4x ledger for a conservative car loading (2,000lb wheel load into three joists = 666 lbs/ft on the ledger with perpindicular to ledger loads = 880 lbs allowable) with Ltt19 straps 36" o.c. min to satisfy perpindicular to wall loads (usually a retaining wall). Contractors usually want to just bear the joists directly on the wall, but I dont like that because of the dirt contact at the top of the wall and required flashing and potential bearing on the PT rim joist itself. The other option i was exploring was a joist pocket ledge in a 10" or 12" thick wall, leaving a minimum 6" thick for the stem wall, 4-6" bearing for the joists resting on a 2x4 or 2x6 pt ledger with standard anchor bolts and a35 clips for load transfers. Additionally the 'left' and 'right' side of the garage joists would have to be P.T. and could be lagged into the concrete for shear transfer (simpson concrete screws redhead..)