# Who knows the magic behind lag bolting a ledger board?



## rktect 1 (Feb 5, 2010)

I have an existing garage that is to remain.  All four walls.   A new floor is being added to replace the ceiling for a bonus room above.  11.875 TJI's at 16" o.c.  These will not bear on the existing top plates.  Instead, a 2x12 will be bolted to the existing stud walls.  One, 1/2" dia. bolt per stud.  ??? Maybe 16" o.c. maybe 24" o.c who knows.  At any rate, the TJI's will be attached to the 2x12 by means of joist hangers.  Above the existing top plates will be built the new addition using 2x4's @ 16" o.c.

Anybody know the magic rule for figuring out if one 1/2" dia lag bolt every 16"-24" is sufficient for this loading?  Garage spans about 21 feet by 21 feet.  30 live load 10 dead load.

I've got a stamp/seal on this one but no calcs.


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## peach (Feb 5, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

nope.. no magic.. depends on snow, wind, rain, etc...  it's a framing practice... mostly for decks..   30 psf.. you're looking at this as a bedroom, not other areas, I guess..

If you know how to read the calcs.. ask for them.. otherwise.. if you can't find the code reference in the Code, I'd (maybe) accept them... I'm not in your shoes..


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## rktect 1 (Feb 5, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

He is calling it a bonus room but it looks like a bedroom.  I suppose I could get the 40 live load then, right?  But still "show me the calcs" sounds a bit pathetic at this point.  The only loads will be the floor live/dead loads so.....  so at 16" o.c.x10.5 feet=13.125 square feetx50ll/dl=656#per bolt.  Okay, now what?  I am certain the bolt won't shear but uncertain that the bolt will not pull right out of the studs.


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## Uncle Bob (Feb 5, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

RKTECT,

"These will not bear on the existing top plates. Instead, a 2x12 will be bolted to the existing stud walls."

I went through this about 4 years ago with a major home builder and their Engineers.  You can't "load-side" the walls!

 I have the information on my computer that is in storage; but, hopefully someone here has the necessary information.

Unless, of course, the NAHB has changed the IRC to allow it.  Maybe this weekend; I'll find the information.

Please, please don't side-load the walls,

Uncle Bob


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## rktect 1 (Feb 5, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

Thanks UB.

I hope you can find the info or someone else has it.

Would it be archived on that other code forum site?


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## Uncle Bob (Feb 5, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

rktect,

I don't think I'm going to be able to find it; however, if you "really" must sideload the wall; consider using the Simpson lag bolts that are used for decks.  I have seen them used to secure ledger boards to studs.  They are 1/4 inch diameter and should attach to the studs without splitting the stud.  I think they were installed 4" on center to the studs, and a minimum of 2" from top and bottom of the ledger.

(scroll down to page eight (8) to see the lag bolts and how they are used on decks)

http://www.strongtie.com/ftp/fliers/F-DECKCODE09.pdf

If you need the load capabilities of each bolt; call APA help desk and they will help you; these folks are great;

http://www.apawood.org/level_b.cfm?cont ... _help_main

ps: I contacted the APA Help Desk and invited them to join us.  They used to check the old BB and help answer questions about Engineered wood products and installation.

Uncle Bob


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## RickAstoria (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?



			
				rktect 1 said:
			
		

> He is calling it a bonus room but it looks like a bedroom.  I suppose I could get the 40 live load then, right?  But still "show me the calcs" sounds a bit pathetic at this point.  The only loads will be the floor live/dead loads so.....  so at 16" o.c.x10.5 feet=13.125 square feetx50ll/dl=656#per bolt.  Okay, now what?  I am certain the bolt won't shear but uncertain that the bolt will not pull right out of the studs.


What is a "Bonus" room. Rooms are to be documented by terms that are descriptive of its use. Bedrooms aka sleeping rooms. Clearly understood. What is a "Bonus" room. Colloquial terms are not acceptable room names. It has to be clearly defined by terms well established dictionary terms found in common dictionary or common trade dictionary terms.

It shall be clearly explained what the room is used for. I know what the colloquial terminology is but it is a fancy way to try to give you a term to describe the room without describing its use at all. It is simply a "I don't know and if I did, I'm not telling you how this room is going to be used" statement. If I was the B.O., I'd say, 'unacceptable room label' for the plans. You need to define the primary function of the rooms. Yes, bedrooms maybe used for more then sleeping but that is the primary function of the room for sake of defining appropriate code requirements like floor live load use.

All function areas must clearly be defined and the function area must clearly define the primary function of the space.

It must be clear. When someone tries to use those terms, I would find it A) an attempt to be deceptive and B) not being forthright and candid with all matters regarding the plan review/permitting & construction process and C) Trying to get away with not having to meet the legal code requirements.

It would be grounds for R105.6 to kick in.


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## GHRoberts (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

I think that it is clear that a bonus room requires the 40 pound per sqft that specif rooms reguire, egress windows that bedrooms require, and ....

I don't think that room name any less descriptive than "bedroom" is in a 4 bedroom home occupied by a single individual.

Uncle Bob ---

Side loading of studs is not improper. One needs engineering like the math that shows the bolts need to support 650 pounds of shear. The NDS for Wood Construction should have withdrawal and dowel compression numbers that one can play with.


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## kilitact (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

I agree with GHRoberts, except for the need to not be descriptive. Section R106.1.1 provides the authority to ask that the applicant provide all of the details. Is a bonus room or a rompus room a bedroom? Could make a big difference in size of septic tanks and/or egress windows.


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## Plans Approver (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

The code says the live load for *sleeping rooms* is 30 psf. Bathrooms, closets or halls are not sleeping rooms. Bonus room, study, office, game room, study area, etc., are 40 psf. The function drives the loading; where sleeping is the sole, primary function whether called bedroom, sleeping loft, nursery, or a half dozen other terms; the LL is 30 psf.  If bedrooms, closets, halls, bathrooms share the same joists, the load is 40 psf.

[Edit]: GHRoberts and kilitact posted while I was writing, I agree w/ them also.


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## Plans Approver (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

Just for the heck of it. I ran your problem through the I-Level software from Weyerhauser (TrusJoist MacMillan). Using a 21' span and 40 psf. Joists probably won't be 24" oc., could be 16" oc with their heaviest and most expensive joists. Here is the list of possible joists the software came up with. The "X" means can not be used. The boxed "1.77" is the most economical joist the software determined. The software determined that a Simpson IUT3512 face mount hanger or Simpson ITS2.37/11.88 top mount hanger would be required.







*Disclaimer:* _The above should not be relied on for any purpose whatsoever. This is discussion material, not an engineering or design solution, opinion, or judgment._


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## Uncle Bob (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

GH,

Thanks, for the correction on Engineered sideloading.  The requirements that I was refering to was floor framing with dimentional lumber in accordance with the prescriptive code requirements of the 2006 IRC.

Bad UB, bad,   

Uncle Bob


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## Phil (Feb 6, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

rktect,

The magic method is to cirlce the lag bolt on the drawing with a red pen  and write "Justify Connection Capacity." To get a general idea of a lag bolts capacity, the AWC has an online calculator. It doesn't calculate capacity of groups or flag poor details. But, it can give you a general idea of a lag bolts capacity. http://www.awc.org/calculators/index.html .


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## rktect 1 (Feb 8, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

Any other thoughts on this one today?


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## rktect 1 (Feb 8, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

It just dawned on me.  I use the AWC Prescriptive Residential Wood Deck Construction Guide for all wood decks that come in.

On page 12 it has table 5 that lists fastner spacing for a ledger board being attached to a rim joist/band joist with 15/32" sheathing.  The span I have actually exceeds this table.  Also, the arkitect wants to run the 1/2" lag screws into 1.5" wide studs and not a rim joist.  But if he were at a span of 18'-0" he would need lag screws spaced at 10" o.c.

Anybody know how I can base a note for an exterior deck system on the interior floor system using this table?


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## brudgers (Feb 8, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

Are you designing it or reviewing it?


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## rktect 1 (Feb 8, 2010)

Re: Who knows the magic behind lag bolting a ledger board?



			
				brudgers said:
			
		

> Are you designing it or reviewing it?


Review of course.  I hope that doesn't mean I am not allowed to explore solutions to satisfy my own curiosity or to help frame the review comment.


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## Robert Ellenberg (Feb 8, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

Is the description of using a 1x4 ribbon strip and nailing to the adjacent stud referred to in R502.6 Bearing, of the IRC, a type of side loading?  They don't show a diagram but I believe that is what it is.


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## brudgers (Feb 8, 2010)

Re: Who knows the magic behind lag bolting a ledger board?



			
				rktect 1 said:
			
		

> brudgers said:
> 
> 
> 
> > Are you designing it or reviewing it?


Review of course.  I hope that doesn't mean I am not allowed to explore solutions to satisfy my own curiosity or to help frame the review comment.

I was just curious.

I've calc'd nailed ledgers using NDS.

Sounds like you're at about 500 lbs/ft.


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## Big Mac (Feb 16, 2010)

Re: Who knows the magic behind lag bolting a ledger board?

If unable to precisely determine what the applicant's intent is, I would view this as an exercise in worst case scenario plan review.  Worst case floor loading for a residence = 40PSF plus dead loads (probably at least 10PSF) for a total weight of 50PSF X's 1/2 the span = 50psf X's 10.5 = 525PLF.  If studs are 16" on center that equals 700 pounds, if 24" on center that equals 1,050PLF.  I think it is highly unlikley that a 1/2" diameter lag bolt is going to support 1,050PLF without crushing the fibers of the stud and the rim board.  It may even happen with the 700PLF loads.

If unable or unwilling to make the statement that this is or could be used as a sleeping room, then escape windows and smoke detectors are required.


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