What size lag screws for attaching header?

[That One Guy]

I'm using 2x10s as header material for floor I-joists in my loft.  The header will be attached to the wall every 24"o/c with lag screws.  I'm not sure what size and length lag screw will suffice for this application.

I'm guessing either 1/4" or 5/16", 3.5" in length, 2 per stud spaced every 24"

One end of the I-joists will be attached to the header with I-joist hangers.  The other end will terminate on the top plate of an 8' wall utilizing either rim board or 2x10s that the I-joists will be nailed off to.  The I-joists will be 12' long.

Anybody have any input about lag screw sizing?  Any feedback will be appreciaited.  

[glenn kangiser]

Any chance you could make a sketch with Paint - (standard program on windows) - save as jpeg and post it here so we can understand better what you are doing?  Thanks.

[PEG688]

Sounds like ledger to me , could you let it into the studs? Your wall framing must be 2' OC hence the 2 " OC pattern.  Will it be inspeced by a building inspector / dept.? If so I'd ask them what they want.

If no insp. could you bring the I joist beside the stud and put another stud (really a trimmer stud) under the joist? then fire / solid block the stud bay so the joist can't roll ? You'll need the blocking some where in that stud bay anyway , either for fire seperation , anti rotation of the joist , or sheet rock backing above the joist so the blocking going to be used some place either way you do it .

Hope this helps , never ask a welder a carpenter question Eh Glenn    

[That One Guy]

Please excuse my terminology.  Its helps to effectively communicate once in a while.  I meant ledger instead of header.  The ledger is already nailed in place.  I just need to secure it properly with lag screws before the hangers and I-joists are mounted.  Again, I'm looking for a size lag screw that will  suffice.  1/4''? 5/16"? 3/8"?  Maybe 3.5" in length.

[PEG688]

1/2" x 3 1/2 " pre drill so you don't split the studs , you could go to 4" lenght if the studs are 2x6. Keep them
(the lag screws)  spread as far as possible , 1 1/2 " from the edges of the ledger . 2 per stud should be good even if it's is to be inspected unless your in a "high zone" IE earthquake / wind / etc . area.

G/L PEG  

[John Raabe]

Here's a note in my code information:
a 1/2" dia. lag screw can support about 470 lbs in shear. From JLC, 12/94 p 66.

Two will carry about 940 lbs. Your loft might have 30 psf live load and 10 psf dead (material) load. One stud with two bolts could then support over 23 sf of loft. I expect there is less than that going to each stud.

A 3/8" or 1/4" bolt would have less shear support but I do not have a number for them.

[glenn kangiser]

I was just trying to hold his interest until the carpenters got out of bed, PEG.

[PEG688]

I was just trying to hold his interest until the carpenters got out of bed, PEG.

We need our beauty sleep ya know   All that sun, wind and rain takes it's toll Good job Glenn