I’m new to the remodeling trade. I have a question about the building of headers, ridge beams, and ledgers. The company I work for uses glue nails and lag bolts to build double and triple beams. I understand the glue and nails but do you need to bolt these beams with lag bolts?
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There's a bit of engineering involved in building the beams you describe, although in most residential applications with moderate spans and loads, us ordinary carpenters can usually nail and glue up a beam that's more than serviceable.
When I've built up beams that need to carry a critical load and/or bridge a span of 12 feet or more, I usually refer the specs already calculated and designed. I have a couple of older books that provide this information (unfortunately, they're boxed up right now and not readily available, so I can't provide titles, etc., at the moment, but maybe someone else out there will offer those references).
As to lag bolts: Personally, I consider them "the bolt of last resort" because they're little more than an oversized ring shank nail for withdrawal strength and have less shear strength than a through-bolt of equal size. When I've made up beams that call for bolts, I bolt them through with washers on both sides if machine bolts, or on the nut side with carriage bolts.
Now I'm not saying that lag bolts don't have their place but I've seen lags used in a lot of applications that make me cringe, like putting together the main wooden structural members for kids playground equipment, etc.
And I wouldn't think their use in built up beams would offer much benefit over through bolts given the work and expense involved.
You are right about that. Someone else pointed out recently that there is no such thing as lag bolts - ever try to find a nut to fit one?
Through bolts is a redundant bit of phraseology but clear and probably necessary to make the point. They keep the separate pieces from spreading apart and acting separately under stress.
When engineers spec bolts and a bolt pattern, it is essential to follow it to avoid liability.
Excellence is its own reward!
Glad you agree. My formal training long ago was as a construction millwright and it was beaten in to us that lag bolts were "farmer bolts" (no offense to farmers by me, just passing on the training jargon) and had no place in the kind of work we were doing.
Consequently, when I drifted into the carpentry construction trade, I was uncomfortable with the commonplace use of lag bolts...kind of like suddenly finding yourself expected to wear a dress.
I do use them now on occasion but only when necessary and always with pilot holes. It's REALLY amazing to see someone drive them in from start to finish with a sledge hammer!
Hey Notchy...I bet you're cute in a dress :)
Sorry, but I've got knees that resemble door knobs.
Everything I ever learned about structure, ( Which is not a lot, ) is what goes up wants to come down, badly.
In regards to reason and descision making , when given the choice. stacking things up is far superior to pinning them together.
Anytime you rely on a metal fastener to carry your load, you are relying on the strength of the metal to fight gravity.
That does not even begin to speak to flexing and weather.
Imho The thru bolts are not carrying the load , the beam is carrying the load, or should be.
Although in an extreme load, the bolts my help the beam from failing. They should not be used for that reason. The beam should carry the load, without the bolts, without failing
The nails & glue should keep it together.
The thru bolts should keep it together better, if you need better. But not to gain strength but for security.
"I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
Fact is that the screws, nails and construction adhesive will not hold it together as well as thru bolts.
The point is not that the bolts are holding anything UP. They are holding it TOGETHER. The beam is not a beam until it has enough strength to bear the load. Until then it is two, three or four separate structural memebers. It is their total combined function that does the job. I'm sure Boss can show us a few piles of truss parts. No-one will expect that pile of chords and segements to do much individually until properly combined. It is the total design and construction and installation that does the job, not the strength of any single member. Your point of relying on one or another of the components is therfore flawed.
So keep it together man.
)Excellence is its own reward!
Isn't that what i said? I think you need to read more carefully. And Once again what are you building anyway? I was answerng in terms of headers, and deck beams etc. I can see your point if your Building a floor girt. But isn't it standard to use steel. Yes bolts are better, but they are not the norm , nor are they an excuse to use smaller dimensions. Just my Opinion.
"I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
Edited 8/9/2002 8:21:02 AM ET by Edgar76b
Edited 8/9/2002 1:10:19 PM ET by Edgar76b
Edited 8/9/2002 7:11:28 PM ET by Edgar76b
Huh?????????
No it is not what you said.
"The beam should carry the load, without the bolts, without failing.
The nails & glue should keep it together.
The thru bolts should keep it together better, if you need better."
is what you said. We agree that you need to keep all the individual pieces together as a single unit to acheive the designed strength but we do not agree about fasteners. Engineers design beams with glue and bolts. Leave the bolts out and plan on failure. Put them in and any failure ios the engineers liability.
Excellence is its own reward!
Right On."I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
The thing that drives me nuts is when people bolt 2 x 12 rim joists to the posts of a deck Then run the joists into joist hanger. You are relying on those joist hangers to carry your load . I see it all the time around here.
Last month I fixed one like that. It was 6' in the air, the rim joists were only Nailed! Hand nailed. It wasn't very big, but they used No joist hangers! Of course, the one corner gave out after years of surfing up top.
So, I jacked it back up, Bolted a 2 x 8 to the posts under the span of all joists, on both ends. And bolted all of the rim joists to posts. and added some cross bracing. All of which would have been un neccesary if it would have been stacked. They'd have gotton a few more years out of it. If some one would have spent the extra $50 bucks in the first place. Pay now or Pay later. Lucky it was a small deck , And lucky no one was hurt.
Even now that deck is relying on the shear strength of those 1/2" bolts not the 2 x 8.
Another thing about bolting beams beside the fact that it keeps them toghether. I think that a beam with Thru-Bolts, staggered, diagonally, say every 2 feet or less, along the length of the beam decreases the amount of deflection a beam might have. It acts like a Truss, by adding cross bracing ,in a way.
"I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
Edited 8/10/2002 9:09:48 AM ET by Edgar76b
Edited 8/10/2002 9:11:14 AM ET by Edgar76b
"I think that a beam with Thru-Bolts, staggered, diagonally, say every 2 feet or less, along the length of the beam decreases the amount of deflection a beam might have. It acts like a Truss, by adding cross bracing ,in a way."
Bolts couldn't really do either. At best, they might connect the weakest member to the stronger one. (Like if one had a big knot) But that's about it. The only way the bolts would act like a "truss" is if they were connected somehow by metal straps or something.
Drilling the bolt holes actually weakens the beam a bit.
When everything's coming your way, you're in the wrong lane.
Age before beauty my friend. I agree with the point about weakening the beam I hope i haven't offended you. All of my knowledge comes from experience. I have never built any thing that required a bolted beam. And i guess i must concede, that i don't see any use That wouldn't be better served by steel. "I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
It would take quite a bit more than that to offend me.
If your brain itched, could you scratch it by thinking about sandpaper?
I'm sorry, man but I'm having a hrad time seeing where you are coming from in explaining this.
"You are relying on those joist hangers to carry your load ."
That's right, Joist hangers are designed to carry the load. Or are you somehow indicating a regular joist hanger is being used as a beam hanger at the end of the rim joist?
"Bolted a 2 x 8 to the posts under the span of all joists"
Are you saying that you are now using a single 2x8 as a beam to support all the joists for a deck? Hmmm...
There is no benefit to your staggerd bolt placement suggestions other than to satisfy your instincts. Every engineered spec for a built beam I have ever seen places pairs, vertically arranged at specified intervals and distances from the edges, with good reason.
I certainly accept that you are setting a goal of doing one better than you find ahead of you on jobs and want to do ir right. Just be careful about giving design/engineering advice without being sure that it is correct. Someone can get hurt by misinterpreting what you say or applying it to a nontypical situation.
Now if we're talking pet peeves on framing, I hate to see someone end nail through the rim into the joist, and expect nothing but the nails to hold the joists up. No wall or beam under, no joist hangers, no toenails, no ledger board!
Excellence is its own reward!
Edited 8/10/2002 2:22:39 PM ET by piffin
It is my professional Opinion , A beam over which joists are carried, Assuming it is rated to carry that load, is 100% stronger, in terms of carrying Joists, than any joist hanger. that is what i am saying. That is what i have been saying, and I appologize, If I didn't do it very well. I appreciate you taking so much time to try and understand me.
Concerning the deck, I believe that all decks in my area which were nailed to the post. with out the benifit of joist hangers will be providing job security to the carpenters for many years. The design should outlast the lumber . Which is a whole other topic. Lumber.
I had to go over the entire deck adding screws and lags and bolts , which should have been added in the first place. If it were bigger than it was I would have insisted, that it be rebuilt. No one will get hurt on my work."I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
I have built countless beams and headers. Rarely have I seen specifications for built up beams (beams made from multiple pieces of lumber) that require bolts. The exception is flitch beams which of course can't be nailed. All the nailing schedules I have seen for LVL's require nails. Glue never hurts, but bolts are just alot of extra work. Same for girder trusses, always nailed, never bolted.
Now, as for joist hangers, they are not all created equal. When the proper size joist hanger is used with the nails approved by the mfg. they will support the design loads for that size joist. For example, a 2x12 joist is rated to span 15+ feet. The joist hanger mfg. figures a design load of perhaps 55# per foot and designs it's hangers to support that load plus a safety factor of (usually) 4. So, 55#x8=440# (half the length), 440#x4=1760#, my guess is that this is the point at which the hanger may fail.
Now, beams are a different matter and require a heavier hanger with bigger nails. Designed for the loads they carry. That is why you need to know the end reaction of a beam to specify a hanger.
When you bolt (or lag screw) a 2x to a house in order to build a deck, you are not bolting on a beam. You are bolting on a board to recieve joist hangers. Our code requires 2, 1/2" lag screws every 16". Yes, through bolts are stronger, but how much extra work are you willing to go through to male it stronger than it has to be. Keep in mind that the current code is in response to many decks that have failed. Most fail because of a combination of vertical and lateral loads. Most of those because the ledger was nailed to the wall with 16d nails.
Actually, the max load for hangers isn't a safety factor of 4. The allowable load is the lowest value of 3 things:
1. The capacity of the fasteners
2. The average test ultimate divided by 3.
3. The load that causes 1/8" of hanger deflection.
In the 60's people took acid to make the world weird. Now the world is weird and people take Prozac to make it normal.
I wonder if kevin got what he wanted?"I was born in the country, razed in the city, I'm a natural born shaker from my hips to the ground"
What's all this glue stuff? Does that mean all my beams are gonna start to squeak?no turn left unstoned
I use glue/adhesive like crazy. One guy working for me said that he had never seen anybody use glue and A-35s like I do!
But I don't have too much confidernce in glue on LVLs because with the wax they put on them for protection, it just doesn't do much good.Excellence is its own reward!
Now it's my turn to apologize. I think we are talking about too many different types of applications here, which just goes to point up how dangerous it can be to get structural advice over the web.
I didn't mean someone could get hurt on your work. I meant that an interpretation of your written advice could give someone the wrong idea, which would lead to a bad application and possibly, a dangerous situation.
I understand the frustration with poor quality work. Three years ago I was underbid on a job (It was one I really didn't want anyway - I seldom do bid work) and then somebody told me things like, "You ought to do ___________ this way, because contractor X does and he's less expensive than you" I shrugged an "Oh Well"
Today, I stopped by to visit the new owners of that house. First thinbg they wanted fixed was the ____________ bnecause it was falling apart.
Job security is nice tho'Excellence is its own reward!
Response primarily to original post.
Lag bolt IMHO ar primarily for shear, as previously post stated as being oversize nails. Sister joist/beams have no benefit from lag bolts and are only a way , as you describe, to add markup to customer. (one caveat, very slight overturning moment contributions).
BIG contribution if you lag a steel plate to the bottom of a beam. That's a whole different story and discussion.
Lots of interesting comments here. Never heard lag bolts called "Farmer Bolts".
First thing to do is consider WHY you're tying the plies together. A beam that has all the loading coming into one side requires fasteners to carry the load through to the other ply or plies. This would be the case for a header at the end of a balcony, for example. All the load ties into one side and there's no load on the other. The specifier of the beam should come up with a fastener schedule, and it's pretty important. Bolts might be needed in a case like this due to the amount of load that need transferred.
If a beam is evenly loaded it doesn't need as much fastening. An example of a beam like this would be a beam under the floor in a basement, where the floor members sit on top of the entire beam. The specifier of the beam should still call out the fastening schedule, but not as many fasteners should be needed.
Q. Why do blondes get confused in the bathroom?
A. They have to pull their own pants down.
Back to the original Q.......no, I've never done it that way......or seen a simple header done that way......just glued and nailed.......but there might be a good reason.....so.......ask who ever's in charge of the lag bolts...and report back here with the answer.
Maybe we'll all learn something new. Thanks, Jeff
.......Sometimes on the toll road of life.....a handful of change is good.......
I guess the question I asked about gluing, nailing and bolting beams and headers togeather has more then one answer and a lot of opinions. Is it possible that a code book could give me a answer that would be the minimum requirements If so what books should I be reading? As I said in my first question I'm new to this trade after working 18 years in the machining trade. Any good books you could suggest would be appriciated
Thanks
all codes are local. Call the local building inspector's office and ask what they recommend. They'll usually have a pamphlet for two on specific scopes of work. Or, they can tell ya what codes apply.
Remember...they're paid with your tax money...don't be afraid to ask questions...it's their job to answer. Jeff.......Sometimes on the toll road of life.....a handful of change is good.......
Jeff, not paid from taxes in all places. permit fees are designed to cover dept costs here so that new growth isn't paid for by existing residents. Still same conclusion tho'. They are public servants.Excellence is its own reward!
I think that alot of us have seen beams built a number of ways, and each for their own application. Every house that we do has about every beam applied, glulam, LVL, built up 2, 4, and 6 ply, and steel. The applications of such are so varied with so many different house designs, I don't think there is a book or "manual" out there, nor would I think that any writer would want that responsibility on thier shoulders.
I will say that blueprints are about as much varied as there are beams...(from the 56 page one we have now to a paper napkin we have built off of). I find myself personally calling the Inginere (no offense meant guys) to specifially call out what he/she is intending for the application. There are the "standards" by which to build headers and such, but clarifying ANY questions that you will come up across over time is well worth the cell phone call IMHO.
Edited 8/13/2002 8:19:33 PM ET by POSTNBEAM
Kevin:
If you want to find out how AND why rather than "just do it this way", one of the best straightforward texts I've seen is "Elements of strength of material", by Timeshenko and Young. Only about an inch thick. The version I have is from the early 60's, likely later editions. Not a code book but it will tell you without knowing calculus how to figure out when things will yield and when they will break.
PS: I did a 2 minute check of Amazon and a few other places, all said it was in 5th edition but out of print - ask at the library .
PPS: there is a section in "machinery handbook" (which you likely are familiar with) with straightforward beam formula and methods.
Edited 8/13/2002 11:47:45 PM ET by JUNKHOUND