Wood Screw Lateral Strength in Edge of 2X 1

[waytsh]

Got a call today from a builder looking to have us specify the fasteners for a ledger board supporting some small garage wood trusses. Fortunately the inspector called them out on it. See attached sketch. The black is what they currently have out there. I know, I know. The red is what I am proposing to add. Two more screws per location and jack or cripple studs between the double top plates and the gable rafter to pick up those screws. Probably at 16" o.c. to get the capacity I need. For clarity I am not showing the jack stud connection to the surrounding framing.

My question is mainly focused on determining the capacity of the screws already installed into the edge of the top plates. The end grain factor should not apply but is there some other reduction of for the lateral load 90 degrees to the wood grain and so close to an edge? I feel like I might be missing something here. Thanks in advance.

 

[KootK]

Any chance you could get away with not counting the black screws at all? With a blind install into such a narrow face, I could see the actual install being pretty disappointing. I have the same concern with the red screws to a degree but at least you're pushing into parallel to grain material there.

If you only use the red screws, I suppose that you'd have to worry some about just ripping away a chunk of the top.

HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[waytsh]

Hi KootK,

Yes, that is certainly a valid concern. The worst case truss hanger load is 700# so I may need to tighten up the spacing of the studs there. The rest of the truss loads taper off quickly as they are hip trusses and very lightly loaded so I could probably ignore the installed screws as I move down slope. Trusses are spaced at typical 24" o.c.

I will check out your thread. Looks very interesting.

Thanks!

 

[dhengr]

Waytsh:
Stand a 2x10 on edge, on top of the double top pl. It will show in x-section just as you show the existing 2x rafter, and the new 2x6 jack studs will be notched around it the same too. Then you have the edge dist. and some latitude to install all the red lags you want. The black lags do not have enough edge dist. into the 1.5” edge of the 2x6 top pl. to be at all effective in loading perp. to the grain, assuming they actually hit the 2x6 edge at all.

Edit: Otherwise, the lags will more than likely split the 2x6 top pl. when installed into the edge of it. So, they won’t have any holding value in shear or in tension.

 

[waytsh]

Thanks dheng. I did have that as as second option although I had not added the jack studs as you suggested (see attached) It is a good suggestion as it will eliminate the risk of missing the jack studs with the red screws. I was actually leaning towards that option initially but the contractor wanted to use the studs instead. He is not going to get his way on this one and will have to deal with adding the band board.

 

[oldestguy]

Where splitting is a risk, what about carriage bolts and stacked washers?

 

[waytsh]

So I got some more information on the truss loading today and it is not good news. It turns out the truss loading is much heavier than I had initially been lead to believe. My worst case is a line of four trusses at 24" o.c. with a loading of 3,449#, 1,547#, 1,724#, and 2,812#. After that the loading drops off to only a couple hundred pounds per truss. It looks like the only way I am going to have a chance of getting this to work is with the through bolts.