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Ledger board


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07-10-09, 10:07 AM   #1  
Ledger board

Hi all, I have a question about ledger boards. I am rebuilding a second floor to my old barn. I am going to use 20" tall x 6" wide steel I beams for a large span. I want to use 12" joists then for the floor. It should be able to support car projects and parts. I wondered if I use a ledger board if I should use thicker than a 2x6. Say like maybe two 2x6 together so that more of the joist sits on the ledger. I want it to be really strong. Best would be to lay both joists on the I beam, but I don't want to give up 12 inches for this. I already am having to change the entrance slope 10" higher. Also the bolts holes for the ledger are already drilled. What do you guys say. Does a thicker ledger give any more strength? For supporting a lot of weight can I still use a ledger and get the same strength as joists lying across? Thanks for your responses in advance -Mike

 
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07-10-09, 04:57 PM   #2  
The way you put things I do not entirely follow. But I presume your ledgers are on the outside walls and the giant beam is down the middle? If so, often like with balloon framing, they will notch the ledger into the studs. Even partially notched helps transfer weight to studs without relying entirely on fasteners.

But it kinda sounds like you are past that stage, and are hoping to shorten the distance by fastening another ledger to the already anchored ledger? If you set the 2 x 12's out only on the inner ledger only (trying to shorten the span) you then put an additional leverage type load at where it fastens to the outer wall.

Imagine carrying this out to some ridiculous illustration where say you keep on bolting more and more ledgers atop one another so that you are say, 2 feet out from the outside wall. And then you set the edge of the 2 x 12 joist on only about the last 2 inches of that 2 foot ledger. You can see how this will try to push down on that ledger and tear out the fasteners by a form of leverage - in theory.

 
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07-11-09, 08:49 PM   #3  
Thanks

Thanks for your response. Notching is a great idea, I could also use a 2x12 for the ledger and notch it so that 6" stays below and 6" is notched. I am sorry I was not clear. The ledger board sits inside the I-beam. The I beam is 20" fits 2x6"ledger +2x12" joist for 20" roughly. My home building book talks how your joists should rest 3-4" on the foundation wall. I was just thinking a joist resting on a 1.5" width of the ledger might not be enough. The other thing is not sure if a 2x6 is strong enough for the ledger but should be I think since the span is only like every 4 feet (support bolts every 4 ft).

Posted By: ecman51` The way you put things I do not entirely follow. But I presume your ledgers are on the outside walls and the giant beam is down the middle? If so, often like with balloon framing, they will notch the ledger into the studs. Even partially notched helps transfer weight to studs without relying entirely on fasteners.

But it kinda sounds like you are past that stage, and are hoping to shorten the distance by fastening another ledger to the already anchored ledger? If you set the 2 x 12's out only on the inner ledger only (trying to shorten the span) you then put an additional leverage type load at where it fastens to the outer wall.

Imagine carrying this out to some ridiculous illustration where say you keep on bolting more and more ledgers atop one another so that you are say, 2 feet out from the outside wall. And then you set the edge of the 2 x 12 joist on only about the last 2 inches of that 2 foot ledger. You can see how this will try to push down on that ledger and tear out the fasteners by a form of leverage - in theory.

 
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07-12-09, 11:40 AM   #4  
Hmmmm. You mean to tell me the 2 x 12's are going to go basically in between the horizontal flat parts of the I-beam? That the 2 x 12's will not be resting on the very top of the I-beam, and crossing the mid-point? That isn't kosher.

The weight of the floor needs to be on the vertical 20 inch part of the I-beam! Whatever you do, do not rely on the load to be carried by the bottom horizontal part of the I-beam! An I-beam is meant to have a load transfer down the vertical part.

The reason for the top and bottom flat parts of an I-beam is to keep the I-beam from twisting, so that the vertical part stays rigid and in place, without twisting or buckling. And also the top is meant as a place to rest the load. The flat bottom part is not there for the purpose to carry a load.

Also, if you notch the 2 x 12's midway, and you do not support the bottom of the notched part, and it just hangs there, you risk the 2 x board splitting at that point.

Will a ledger or a band to the joists, be bolted to the vertical 20 inch metal of the I-beam? That is the only way I can see the strength of the 20 inches doing more of the job, and taking some of the pressure off the bottom horizontal flat part of the I-beam.

I-beams were not made to have the load transfered to one side of the flat horizontal flat piece of the I-beam! Keep that one in mind.

This whole plan sounds unorthodox.

I hope you do not proceed without your understanding of this better, and posting back. I think you will get more replies, also, if everyone understands this more. I think I do, but I have to hope you realize about what you are relying on exactly, with what part of that I-beam, to do the load carrying.

You are dealing with massive sizes here, with wide I-beam and wide joists, and obviously you are designing this for heavy loads. And since you are doing this in an unorthodox way, you should seek professional advise. If nothing else, from an engineer who works at the place where you bought the I-beam!


Last edited by ecman51; 07-12-09 at 11:58 AM.
 
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07-13-09, 06:09 AM   #5  
Thanks again for your response. I was not planning on putting weight on the lower horizontal flange. Its an S beam that gets thicker at the joint. So the joists would want to slide off if I did The ledger board bolts do not go above where the notches would be. So it would be supported under the notched section. These were used beams I bought, so unfortunately I have no engineer involved or supplier to help out.

You say that beams are not designed for side loads. This concerns me as something that could be a problem. The bolt holes for the ledger are closer to the bottom of the beam maybe 3-4" up. I know they were used with a ledger prior to my use. Just the amount of weight they held would have been different.

I have 3 beams total. Each beam will go across the barn with about 12-14 ft inbetween. Also each beam will have joists on both sides. So I wouldn't be loading up just one side of the beam, but I can see there could be a large difference on one side vs the other when I roll a car on top. My assumption though to is the joists on the non-loaded side would help to keep the beam from wanting to twist.

-Mike


Posted By: ecman51` Hmmmm. You mean to tell me the 2 x 12's are going to go basically in between the horizontal flat parts of the I-beam? That the 2 x 12's will not be resting on the very top of the I-beam, and crossing the mid-point? That isn't kosher.

The weight of the floor needs to be on the vertical 20 inch part of the I-beam! Whatever you do, do not rely on the load to be carried by the bottom horizontal part of the I-beam! An I-beam is meant to have a load transfer down the vertical part.

The reason for the top and bottom flat parts of an I-beam is to keep the I-beam from twisting, so that the vertical part stays rigid and in place, without twisting or buckling. And also the top is meant as a place to rest the load. The flat bottom part is not there for the purpose to carry a load.

Also, if you notch the 2 x 12's midway, and you do not support the bottom of the notched part, and it just hangs there, you risk the 2 x board splitting at that point.

Will a ledger or a band to the joists, be bolted to the vertical 20 inch metal of the I-beam? That is the only way I can see the strength of the 20 inches doing more of the job, and taking some of the pressure off the bottom horizontal flat part of the I-beam.

I-beams were not made to have the load transfered to one side of the flat horizontal flat piece of the I-beam! Keep that one in mind.

This whole plan sounds unorthodox.

I hope you do not proceed without your understanding of this better, and posting back. I think you will get more replies, also, if everyone understands this more. I think I do, but I have to hope you realize about what you are relying on exactly, with what part of that I-beam, to do the load carrying.

You are dealing with massive sizes here, with wide I-beam and wide joists, and obviously you are designing this for heavy loads. And since you are doing this in an unorthodox way, you should seek professional advise. If nothing else, from an engineer who works at the place where you bought the I-beam!

 
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07-13-09, 07:05 AM   #6  
Posted By: luo2000 Thanks again for your response. I was not planning on putting weight on the lower horizontal flange. Its an S beam that gets thicker at the joint.
S -beam? ???????

The ledger board bolts do not go above where the notches would be. So it would be supported under the notched section.
I'm just not following now what the beam looks like and how the ledge and notch arrangement is like. Please try to redescribe, paying attention more how you describe this.

I have 3 beams total. Each beam will go across the barn with about 12-14 ft inbetween. Also each beam will have joists on both sides.
This I do follow.

So I wouldn't be loading up just one side of the beam, ......
You misunderstood what I was implying about one side of the beam, when I really should have said about each side of the bottom of the I-beam. I simply wanted to make it clear that on that bottom flange of the i-beam, on each side - is not intended to bear the weight. And now it sounds to me that you understand this and that bottom flange will not be what is carrying the load. That is all I was really trying to instruct on.

As long as you make this so the 20-inch vertical part of the I-beams carry the load, and that by doing any notching you do, that what is underneath the bottom of the 2 x 12's is not just hanging there, unsupported, with 6 inches of the thickness reduced, then, I think that if you follow these 2 things, you wil be all right.

I also do not want you to get the wrong impression about the inability of the I-beam to take a lateral stress. They can. That is the idea of the top and bottom 'flange' as you call them. What I was trying to make clear is what the idea of the top and bottom flanges are for -to keep the I-beam from twisting under load.

Out of curiousity, what is holding up the I-beams on each end?

 
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07-13-09, 08:56 AM   #7  
S standard beam:


Hopefully this picture shows what I plan well enough:


For support I have a thick concrete wall on one end. I am going to use a lolly column on the other end. I am probably going to make a small concrete platform for the column to make sure I have strong concrete spreading out the weight. The concrete is thick there but its also old and I want to make sure I'm not going to punch a hole through. I'm not 100% yet on that though. I wanted to make a concrete pillar with rebar so that each end was supported by concrete and bolted to it. I might add 3 total columns per beam and have one end on the ledge. I haven't decided on that. Span is 34' I am also thinking of welding pipe which goes across the bottom of all the ibeams perpendicular for more strength.

Thanks again -Mike


Posted By: ecman51` S -beam? ???????



I'm just not following now what the beam looks like and how the ledge and notch arrangement is like. Please try to redescribe, paying attention more how you describe this.



This I do follow.



You misunderstood what I was implying about one side of the beam, when I really should have said about each side of the bottom of the I-beam. I simply wanted to make it clear that on that bottom flange of the i-beam, on each side - is not intended to bear the weight. And now it sounds to me that you understand this and that bottom flange will not be what is carrying the load. That is all I was really trying to instruct on.

As long as you make this so the 20-inch vertical part of the I-beams carry the load, and that by doing any notching you do, that what is underneath the bottom of the 2 x 12's is not just hanging there, unsupported, with 6 inches of the thickness reduced, then, I think that if you follow these 2 things, you wil be all right.

I also do not want you to get the wrong impression about the inability of the I-beam to take a lateral stress. They can. That is the idea of the top and bottom 'flange' as you call them. What I was trying to make clear is what the idea of the top and bottom flanges are for -to keep the I-beam from twisting under load.

Out of curiousity, what is holding up the I-beams on each end?

 
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07-13-09, 05:30 PM   #8  
Just what I pictured in my mind. The weak link however is the bolts/the number and diameter of them. I'd imagine that you are indeed relying on some of the load carried by the bottom flange, because I'd imagine the ledger sits on it. But because it gets thicker at the 20 inch vertical, you'll probably be alright.

If the I-beam is cleaned real good so no rust/powder, you might also want to use a strong adhesive behind the ledger. But if you did, you'd have to work fast, and with help, and draw up the ledger to the I-beam tight with clamps before you do the bolting, because the bolting process will take too long. Or, maybe better, you could pre-drill everything and dry fit it first to be sure it will work, and then quickly bolt it all up, with the adhesive. This probably would be faster than clamping, actually.

The wider the amount of ledger that is not notched, the stronger it will be. However, if you cut a tight notch so that the 2 x 12 barely fits in - then in theory, if the ledger were to bow under weight, let's just say(because you did not have enough bolts, and you were not down all the way on that flange), it would have a harder time bowing down because each notch would have to start crushing in each joist, in order to bow.

I actually also toyed (made a drawing) with not notching! - and instead using a 2 x 12 band joist. And then you would have the full strenth of a 2 x 12 you could bolt to the I-beam. And then use the longest joist hanger they make, on each joist (it might be 7 3/4 inches, I am not sure). And then also bolt another 2 x under that band joist, down to the flange, with maybe 3/4 plywood laminated to the bottom ledger, as then that bottom ledger would act like a true ledger, as the joists woud be sitting ontop 3/4 inches of it. That would be very strong!, as it would also assist the top 2 x12 band joist, and also the joists directly.

Other opinions from builders here are obviously welcome. The more the merrier. Get out your pencils and doodle.


Last edited by ecman51; 07-13-09 at 06:15 PM.
 
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07-14-09, 11:11 AM   #9  
More

Thanks. I think your idea is better. In theory the joist hangers should be strong enough but also I would have the 6 inch ledger board to support it as well. Is there any minimum distance for a ledger board? 3/4" doesn't sound like much of a ledge. If I was able to weld the joist hanger to the beam the ledge would only be 1.5" inches vs 2" away from the beam. I've used my mig on mild steel. Most clips are galvanized which I think you need to grind off the coating or deal with the toxic fumes it puts off. Probably not worth it because of how much time it would require.

Another thought maybe is bolting a steel bar like 2x4 or 2x2 where the ledger would be. I could weld at spots along in addition to the bolts.


Posted By: ecman51` Just what I pictured in my mind. The weak link however is the bolts/the number and diameter of them. I'd imagine that you are indeed relying on some of the load carried by the bottom flange, because I'd imagine the ledger sits on it. But because it gets thicker at the 20 inch vertical, you'll probably be alright.

If the I-beam is cleaned real good so no rust/powder, you might also want to use a strong adhesive behind the ledger. But if you did, you'd have to work fast, and with help, and draw up the ledger to the I-beam tight with clamps before you do the bolting, because the bolting process will take too long. Or, maybe better, you could pre-drill everything and dry fit it first to be sure it will work, and then quickly bolt it all up, with the adhesive. This probably would be faster than clamping, actually.

The wider the amount of ledger that is not notched, the stronger it will be. However, if you cut a tight notch so that the 2 x 12 barely fits in - then in theory, if the ledger were to bow under weight, let's just say(because you did not have enough bolts, and you were not down all the way on that flange), it would have a harder time bowing down because each notch would have to start crushing in each joist, in order to bow.

I actually also toyed (made a drawing) with not notching! - and instead using a 2 x 12 band joist. And then you would have the full strenth of a 2 x 12 you could bolt to the I-beam. And then use the longest joist hanger they make, on each joist (it might be 7 3/4 inches, I am not sure). And then also bolt another 2 x under that band joist, down to the flange, with maybe 3/4 plywood laminated to the bottom ledger, as then that bottom ledger would act like a true ledger, as the joists woud be sitting ontop 3/4 inches of it. That would be very strong!, as it would also assist the top 2 x12 band joist, and also the joists directly.

Other opinions from builders here are obviously welcome. The more the merrier. Get out your pencils and doodle.

 
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07-15-09, 04:07 PM   #10  
Don't rush into this project.

I know in my heart there is a best way to this. I have to go back to work now and may not be online again til tomorrow. But for now, I had yet another idea.

I [U]do[/I] know that you really do not want to be solely relying on joist hangers. Especially if full length ones are not available. Shorter ones obviously compromise strength, since you cannot get enough nails into the shorter ones. After all, the the only thing that gives joist hangers their support power is the nails. The thicker the nail used and the more number of nails used, the stronger the support, obviously.

A case in point: Years ago, I built this deck with no lags or bolts through the bandjoist into the 4 x 6 posts. I only used nails. But I pounded in lots of nails(so I thought at the time). Now, years later, the bandjoist and deck have sunk some, causing the deck boards over the 4 x 6 to pop up in the air! I would have never dreamt this in a million years, that with as many nails as I used, that this could happen. Either the galvanized nails have deteriorated, which is possible because treated wood negatively reacts with galvanized, and/or, even though I thought I used a lot, I probably did not use enough. If I used say 8 on each 4 x 6 (but maybe it was 6? -and maybe I used box nails!), you then could add the square inches of nail diameters x 8 to figure out what the equivelant size would be in just one bolt. Maybe 6-8 16d nails would only be like 1 measely 5/16th bolt!

So you want to make sure that enough bolts are used to hold the ledger (and possibly a band joist, if you use my second suggested idea) and the ledger itself is wide enough to not bow - and that the ledger, or a sistered ledger (A 2nd ledger secured to the primary ledger) is under the joists, so that fasteners/hangers are not a sole or primary support system. You want to make it, so the ONLY thing that is really the weak link is the bolts, and nothing else.

I have been doodling with other ideas also, so don't rush into anything just yet. I am toying with the idea also of notching out only 4 inches from your first concept 12"(11 1/4" actual) ledger, rather than 6 inches, and instead notching a couple inches from the bottom of the 2 x 12's, to give the ledger more strength. Then using the 7 3/4 inch joist hangers as well, to help support the non-notched remaining 9 1/4 inches of the 11 1/4 inch joists. Follow this?

But I want to draw this out better.

Til later or tomorrow. At least I have you thinking. And it sounds to me like you are a sharp guy. And if you understand the forces at work here, you can probably solve this as well as me. If you have brains and can sketch, that is what it takes. And keep in mind what the weak links are: What could try to snap. What could try to bow - if elephants were uip there.

 
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07-19-09, 09:50 PM   #11  
I hope you do more reading on the load path for an I-beam and the lateral (turnover) bracing required: steel I beams in framing houses - Google Books

Be safe, G

 
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09-08-09, 12:06 PM   #12  
Back again

Hi, thanks for your responses. I've got the beam near ready. I am changing my layout so that the spans are shorter. Longest span is 10' now and other spans are 8'. Because the span is shorter I am going to be using shorter joists. 10" joists now. I measured the distance in the middle to be about 17". I am going to trim a 10" board to be the ledger. So a 10" ledger and 10" joists rest on that. I plan on making custom hangers out of 2x2x1/8" angle iron. The angle iron will be applied on each side of the joist and be full length. Hopefully all the weight can be carried on the angle iron brackets and bolts. Then the ledger is the failsafe. I haven't figured out exactly what I need as far as how many bolts. Here is what I am thinking: 2 per hanger, 5/16" grade 5 or 8 bolts into the steel beam. - There are two hangers on each side of the joist so its almost as if there were two on top and two on the bottom. I plan on running the bolts through the beam to attach to another hanger on the other side. 4 per joist, 1/4" bolts grade 2 or 5. My concern is that having too many bolts could weaken the area. Having too few would put too much load on one part causing splitting. With four it should be 1.5-2" spacing. On the hangers I'd like to put the bolt holes 1" out. So basically all the bolts on the board go approximately 1" from the edge. I'm not sure if I need farther from the edge or not. I found the shear strengths chart here: SAE Bolt Strength Specs So I am roughly basing it on the second chart. Oh and here is a picture of the 2000lbs beam raised

 
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09-08-09, 04:19 PM   #13  
Thanks for the update. It sounds like you have given this matter great thought.

i used to spend lots of time at a drawing table doing line drawings and analyzing through situations. Some people think that if a probelm arises from the fact they did not have everything figured out well enough in advance, that they could address a problem if it later arose. Sometimes that is not very possible and/or costly.

Keep us updated.

 
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10-28-09, 08:08 AM   #14  
Update

Its coming along. 300 sqft done. I still have to install the permanent lolly columns yet.







This is before I added teh subfloor.

 
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