ledger - stud wall connection w lags shear or bearing

huangyhg

ledger - stud wall connection w/ lags: shear or bearing?
hi everybody,
i am designing a deck w/ a 4000 lbf jacuzzi & 210 psf snow load.  i end up having that each joist (@16" o.c.) bears on the 4x ledger (w/ hanger) with a total load of 1500 lbf.  i want to use lags to connect the ledger to the 2x6 studs in the wall.  using the nds asd table 11j (& applicable factors), i get that i need 3- 3/4" lags @ 16" o.c.  that just seems ridiculous...  also, i am concerned that the large lags will cause the wood to split.  
can it be argued that it is bearing (table 11.3.2), rather than shear that controls?  or do i need to specify a closer lag spacing w/ blocking between studs?
thanks,
cmhski
cmhski,
is the 210 psf a typo?  that would be about 20 to 30 feet of snow!  are you connecting your joists to the face of an existing wall?  what is the cladding?  better connection would be to place studs under joists or provide beam and columns adjacent to wall similar to what you must have on the outer side.  when you say 4x ledger, what do you mean?  in summary, not enough information.      
yeah, like hokie said, check your snow load.  what is the reason you use such a thick ledger?  i think there is a top flange hanger that will support 1500 lb, or you can use face mount hanger.  also, instead of using lag bolt try to use ledgerloks.  go to
that is correct snow load for tahoe (nevada or california).
for those loads, i'd consider using through bolts with rings or modify the detail so that the forces can be transferred by bearing... weld a plate on the top of the ledger and maybe notch the ledger into the studs.
i think your concerns with the lag bolts are well founded.  i know frank woeste at virgina tech has done some extensive research on deck and balcony design, which included the attacment of ledgers.  i think i downloaded it before, but that was a few years back.  i couldn't find it just know, but i didn't try that hard.  it would be worth looking at.  sorry i can't give you a link.
it was an article in the journal of light construction.  i re  
when your loads get that high you probably don't want to count on connecting to the rim board and wall studs to support all your vertical load.  you would be better off adding a girder and posts about 2 ft off from the wall and then your other girder and posts and the end of the deck.  i've designed decks for over 250 psf snow load and hot tubs here in washington and you don't want them pulling away from the structure.  three 3/4" lags into every stud is not a good idea.  the same is true with the ledger lok screws.  they have a slightly higher capacity than regular lag screws but still not a good idea.
if you provide the extra girder for the verticzal loads all your connection to the wall studs will have to resist is the lateral loads for wind and seismic.
really? 210 psf in truckee?  the worst one ive seen in colorado is 110.
well, i guess you can always add girder right next to the wall or frame the joist the other way and rest the girder in the wall.
i would follow rockengineer's advice.  if you are able to, get a copy of "wood design focus" volume 16, number 2 summer 2006.
it has several articles co-authored by frank woeste, p.e. regarding testing that has been done on deck ledger connections and guardrail connections.
i think a review of those articles would discourage you from using lags or through bolts to attach your ledger to the wall studs.
the article rarswc is refering to was what i was talking about.  it was a good artilce and worth reading.