I am sure I have done this somewhere.. sometime… , but I’d like ya all’s imput?
I just finished framing a garage addition for my neighbor. it has a sloped roof/ceiling starting at 10′ and going up to 18′ (shed style attaching to his roof eave).
the garage is 40′ x 16′ –
so now he wants to add a floor at the 10′ level with the same i-joists I used for the rafters. I think it will work to put a 2×12 ledger lag bolted to the studs on each side and put hangers on the ledgers to support the new 12″ i-joists. I hope you guys say it will work and the local building official says it’s proscriptive. (no engineering)
(I also need the floor to line up with his house second story floor)
my other back up idea is to………..all the weight on the lag bolts make me a little nervous? maybe I should cut into the studs 1″ to set the ledger in…?
Replies
Could you set the joists on top of the garage wall? Or maybe use top mount hangers fastened to the wall plate, with a stud behind each joist?
Jon Blakemore
the floor wouldn't line up with the house floor- then - he is hoping to walk out a door into this new attic area from the house. something he will add later...
How far from the top of the joists to the top of the plates?
Jon Blakemore
about 6"
You need to know exactly how far is it from the top of the existing floor joists down to the top of the 10' new garage wall. Or is the 10' new garage wall higher or in the middle of the top of the existing floor joists?
Is the existing house balloon framed because you said that you would bolt a 2x12 ledger to the studs and not a box/rim joist?
How can you make this change without and Architect or Engineer?
Joe Carola
Edited 9/18/2004 8:49 am ET by Framer
the house is not ballon framed - I you are right on the house side my ledger would line up with the rim joist (dah..) so those lag bolts would be into the raim joist.
on the garage wall side I can only hit studs - the plate is too high by 6".
either way - do you think the lab bolts are strong enough? - I saw topic on here about en exterior deck shearing at the bolt line...
Lag bolts are used every day for ledgers. Depending upon where you are some towms call for through bolts with deck ledgers.
You said your using 12" I-joists. You should be using a 1-3/4" x 11-7/8" Microlam for the ledger.
What are you going to do with the 10' wall top plate being higher 6" above the existing floor joists? If it were me I would nail 2x4's horizontally across each stud to hold them in place and then nail 2x4 braces on top to hold the wall in place and remove the top plates and cut the studs down and put the top plates back on and sit the I-joists on top of the plates with a rim board and be done with it then you can run your decking on top and start putting you plates down and frame the second floor.
You can run the I-joists along side the 2x4's and then put 2x4's under the I-joists down to the foundation. This way you'll have the top plate sticking above 6" and then you'll have to frame your second floor walls on top of that which I wouldn't do.
If your top plate is 6" above the floor and you wanted to bolt a ledger into the 10' wall you would have only 3" left of the top of the stud above your ledger. As far as I know you can't bolt into that 2x4 with the end grain.
For me the first way I showed you is the fastest and strongest way to do it. You have no ledgers, no lag bolts and no hangers and you can run your decking all the way out and layout all your plates even and cut all your studs need be at the same length.
Joe Carola
>>>"You should be using a 1-3/4" x 11-7/8" Microlam for the ledger."
Joe, isn't that overkill? If the ledger is properly fastened to the studs the ledger would be spanning 16". A 2x12 would be rock solid spanning 16". Is the LVL more for nail holding characteristics?
Jon Blakemore
I don't think it's overkill at all. The ledger would be 40' and I never mix 2x12's with I-joists because they're not the same size they can vary from 11-1/4" to 11-1/2" and they shrink I-joists don't and they're 11-7/8". I always use 1-3/4" x 11-7/8" Microlam for a ledger when using 12" I-joists. Also the top mount hangers are about 1-3/4" they don't fit on top of a 2x12 at least the top mount hangers I use anyway.
Even when I use 9-1/2" I-joists I use 1-3/4" x 9-1/2" Microlam for ledgers.If you use 2x12 for a ledger do you fill in the gap for sheetrock?
Joe Carola
i may need to send a pic. - the garage is one story with a shed roof starting on top the 10' wall going up to the houses's roof which is a two story house. in other words the house roof is 6/12 and just continues down the garage side to the 10 wall plate. the plate supports the roof i-joists.
I agree on the microlam, I will order that.
The 2x6 wall studs are 16" on center - so I could put my new floor joists alonside them and support them with additional 2x4's or 2x6's. right?
on the other end - (the house side) - the micorlam ledger will attach at the house rim joist thru the t111 siding and osb sheathing with lag bolts - I guess?
or I could cut in siding and osb and sister the mirolam right directly to the rim joist,
by the way, this floor is just an attic/storage area above the garage. but he wants is strong... it will have about 8' headroom down to 6" across the 16' span.
comments?
I understand now. I thought you were going to take the new garage rafters off and use them for the floor joist and then put a complete second floor above that.
All your doing is just adding new I-joist keeping the top even with the top of the existing floor joist without touching the new rafters. Then just do as I said in the second part of my last post and use a Microlam as a ledger and cut the T111 and OSB out and let the ledger sit on top of both them and then bolt the ledger to the existing box and then run the joists along side the 2x6 wall and fill in studs underneath them. I would also keep them in the thickness of a rimboard and nail 14-3/8" rimboard blocks as if it were a box.
Joe Carola
Edited 9/19/2004 9:42 am ET by Framer
Here's a drawing of what I think your talking about.
Anyone know why I couldn't attach this to my previous post?
Joe Carola
very nice drawing- looks like you saw the plans!
do I need a ledger on the right side of the pic. ? it would show if it was underneath the I-joists?
do I need a ledger on the right side of the pic. ? it would show if it was underneath the I-joists?
You wouldn't need a ledger on the right side because your filling in underneath with 2x4 to hold the I-joists up. On the other side I would cut out the T111 and OSB and bolt the ledger right into the existng box.
Look there's a million ways of doing things and over the years I've done them different ways and the way I've told you how to do this I've done before. The ledger side I've always done and never had a problem with I-joists and using 2x's. On the right side of the drawing I've done that plenty of times with 2x material and never had a problem. The right side of the drawing I've never done before with I-joists but I think it will work and think it is a stronger way then bolting a ledger onto the Endgrain of a 2x4 that's only sticking above the top of the I-joists 3". Bolting a ledger uderneath the I-joist might be a option but everything I've ever done before or explained to anyone before was all done from Architectual or Engineered plans so you really have to see what is acceptable.
They're might be some detail on an I-joist situation like I've shown on the rigfht side of the drawing but it's not my call or your call.
Boss has a good point as far as the loads on a ledger and the studs. I've always wondered the same thing but Architects and Engineere keep drawing them this way and we keep framing them this way and so far in all the years I've been framing I've never seen any problems with them.
Joe Carola
Edited 9/19/2004 10:06 am ET by Framer
I'm not a fan of ledgers. They're fine when you're hardly carrying any weight, but not in cases like this.
Doing a little rough math, your ledger will have a design load of about 440 PLF on it. (8' X 55 PSF) If your studs are 16" O.C., that means you have to connect roughly 600# to each stud.
Assuming someone can come up with a way to attach that much load, you'd be O.K. But that's tough to do withy a couple of lag bolts.
Her kisses left something to be desired. The rest of her.
I think the only ledger really needed is on the house side and it will be mated to the rim joist - right? one is a microlam and one is i-beam rim joist material - neither materials will split from the bolt hoes. the only question left is bolt size? and whether the building official will allow lag bolts... not much chance for pull out on the lag bolts - just shear strength is needed.
Doing a little rough math, your ledger will have a design load of about 440 PLF on it. (8' X 55 PSF) If your studs are 16" O.C., that means you have to connect roughly 600# to each stud.
Are those calculations based on him bolting his ledger into the existing box?
Also what do you think about bolting a ledger directly into the center of studs as oppossed to a solid 2x box.
I'm also curious if there's a difference in strength when a ledger is boted to a second floor box with a 2x4 wall underneath as oppossed to a ledger bolted to a first floor box that sits on the mudsill on top of the foundation.
Joe Carola
Edited 9/19/2004 10:13 am ET by Framer
Edited 9/19/2004 11:32 am ET by Framer
I was basing the ~600# load based on bolting the ledger to studs.
Through bolting to another ledger would be a lot better.
I'd never go for lag bolts, personally.Happiness is a conscious choice, not an automatic response.
I am assuming you are running the new I-joist in the 16' direction (which will give me a worst case scenario). With this in mind you will have a total load reaction at the leder board of approx. 416 lbs/ft (8' x 52 psf ) then you transfer the load into the hangers which is fine then the ledger board is supported by the lags into the studs every 16" o.c. which puts the vertical shear force that needs to be transferd by the lags into the studs at 553 lbs (416 * (12/16) ). Without putting you to sleep with what happens next when I go into my AITC manual and derived the allowable load for a lag bolt with 'x' amount of pentration depth into the stud.
I suggest if you cannot feasably work out a better way of supporting the new I joists without using a ledger board then what actually works better than lags are Simpson Strong Drive Screws (SSDC), I suggest SDS 1/4X4". Ledger boards with lags are commonly done but they completely rely on the fact that the max. loading conditions are not acheived. SSDC don't required predrilling and you can put 3 of 'em into a 1-1/2" stud (vertically) and get around 800lbs of vertical shear force transfer at each stud which exceeds your end reaction of the joists. The only problem is building inspector intuition. He wants to see lags because the are big and bulky. Even though you totally destroy the stud when you install them and most likely you cannot meet the min. criteria set forth in the AITC manual regarding spacing, geometry and etc....
When you install a ledger board you also put the existing studs into a combination of bending and axial comprsseion. When you size a stud for a bearing wall the codes do NOT apply any bending to the section. They presume the loads are applied concentrically to the centroid of the section. I am not trying to be a pain in the butt I am just talking frankly about the issues of what you propose. The moment that the studs no need to be able to resist is fairly considerable for a 2x4 or 2x6 section.