Eccentrically Loaded Lag Screws in Shear
Eccentrically Loaded Lag Screws in Shear
(OP)
I'm looking at a ledger design for a residential deck where the contractor wants to connect via lag screws to the rim joist. The problem is that the house is sheathed on the exterior with 1-inch rigid insulation. Unless the contractor removes the insulation (not preferred), there will be an effective 1-inch gap between the ledger and rim joist. Therefore, the screws won't be designed in simple shear and there will be flexural stresses induced into the screw as well. Per the IRC, only a 1/2" gap is permitted when using their tables. Is there any guidance in NDS or similar documents to address this design issue? I see this done with leveling nuts (i.e. light posts) all the time so I figure there must be guidance somewhere.
Thanks!
Thanks!






RE: Eccentrically Loaded Lag Screws in Shear
RE: Eccentrically Loaded Lag Screws in Shear
If this doesn't work out and if removing the insulation is not an option (contractor worried about water penetration), I'll make the connection vertically non-supporting and keep a nominal connection to the house for lateral stability. However, this would require footings near the house, which would then require them to be ~8' deep to meet the house foundation level where undisturbed soil theoretically exists (20 year old house). Alas, this complicates things and increases costs for the owner, so I'd like to be completely sold on the idea if this is the best path.
I'm just throwing ideas out here. Any suggestions welcome.
RE: Eccentrically Loaded Lag Screws in Shear
RE: Eccentrically Loaded Lag Screws in Shear
RE: Eccentrically Loaded Lag Screws in Shear
Mike McCann
MMC Engineering
RE: Eccentrically Loaded Lag Screws in Shear
RE: Eccentrically Loaded Lag Screws in Shear
BA