NDS Table 11J for lag screws

[JStructsteel]

If using the tables for a side member to 2x4 stud walls, I using side member 1.5 thick, main member 3.5 thick and coming up with 344 lbs capacity before reductions based on my spreadsheet.
The tables I get 360lbs
Im not confident thats correct. I use the AWC connector app and get 249 lbs. Anyone help confirm these numbers?

Southern pine, 1/2" lag screw, no threads

Thanks

 

[XR250]

I didn't know anyone used Lags anymore due to the popularity of timber screws (Simpson SDWS etc).

 

[JStructsteel]

Thanks, thats a good point. The code is specific on the fastener and size. Perhaps I need to re-read it to make sure.

 

[XR250]

What is the application?

 

[JStructsteel]

Ledger board to stud wall

 

[XR250]

Not a great use of 1/2" Ø lags. I imagine they exceed NDS limits due to the 1 1/2" dimension of the stud. Also, 1/2"Ø lags require pre-drilling. Even using 1/4" timber screws in this situation can be sketchy as they need to be centered in the narrow face of the stud. That being said, I usually use timber screws or simply nails.

 

[JStructsteel]

Im going to look into the Simpson or GRK screws. I will ignore the code requirement and see if its flagged.

 

[phamENG]

What code requirement?

 

[JStructsteel]

Im using Michigan residential code.

 

[lexpatrie]

The point goes into the main member, if that changes anything.

The NDS tables do round to the nearest 10 pound increment, so you're in the neighborhood.

 

[dik]

If you center them on the stud, 1/2" dia just make it for edge distance (Canadian Code).

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-Dik

 

[lexpatrie]

I suspect there's something incorrect on your inputs in the online connection calculator? 344 versus 360, sure, that could be a tabulated roundup from say 355, so it's 11 pounds, but the online version spitting out 248, that seems like something isn't right.

This sounds like dry use, and the online calculator has two inputs for specific gravity, and the main member, being a stud, is probably something less than SP? Ledger is SP?

I'd consider 3/8" lag screws so you have some tolerance for an off centerline of stud install as these tend to be finicky and the wood splits.

 

[Deker]

Late to the game, but I ran ran your connection through my spreadsheet and got 249 lbs, rounded to 250 lbs, which also matches the value I see in the NDS tables. By "no threads," do you mean that you are using the full-body diameter for the lag screw? I don't think that's possible since you'd need at least 1-1/4" shank penetration into the main member. For that you'd be looking at a minimum 8" long lag which would blow through the stud.