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View Full Version : How big a header do I need for an 8' passthrough



roy1973
12-17-2007, 12:55 AM
Hi,

My wife wants me to cut a pass through hole (8' wide by 3 1/2' high) in the wall separating the dining room from the living room. This is a centrally located load bearing wall near the center of our single story house in southern calif. I'm thinking 2 2"X10"s with 1/2 plywood in between. Overkill or not enough? Also, should I use 1 or 2 jack studs to support the header at each end?

Thanks,

Roy

SolarPowered
12-17-2007, 02:06 AM
You need to have an engineer come out and study this.

Not only is there the issue of enough strength in the header, there are also questions of maintaining shear strength and shear transfer if this is a shearwall, and the transfer to the foundation of what used to be a distributed load, but would be two point loads after the change.

Bill Lacey
12-17-2007, 02:42 AM
Use a 4-ply 1-3/4"x24" LVL with three rows of 5/8" bolts spaced 6" O.C. and stagger them. That "might" hold it up.

O'BrienConstruction
12-17-2007, 04:55 PM
Bill,
Come on 4 ply 24", that can't span 8'. You know better than that. Oh and since its only spanning 8' no nead for jack studs, a couple 8D toenails ought to hold it just fine. After all when you wrap the openings in sheetrock it will bear on that for extra support.

Kevin Ambrose
12-17-2007, 06:03 PM
either look at the prescriptive code book for your area or see post #2

Twin Pillars
12-17-2007, 06:35 PM
Don't forget to use header glue too.

Bill Lacey
12-17-2007, 07:29 PM
Bill,
Come on 4 ply 24", that can't span 8'. You know better than that.

Hey, I justified my guess by saying it "might" work.

parkwest
12-18-2007, 01:03 AM
How old is the house? Is the roof stick-framed? What type of foundation? What is beneath the new bearing points? Will new pads and posts needed to be added? What spans and loads are you including in your calculations? What type of beam load calculating software are you using? What shear loads and wind loads are you using? What Building code book is in effect in your area?

Timbersmith
12-18-2007, 02:35 PM
Depends on how much load is on it.

Toolwhore
12-18-2007, 05:18 PM
The Super Hooty Header Company just came out with a new helium filled titanium header that negates any point load problems in situations such as these. Might be worth a look-see. :)

arnemckinley
12-18-2007, 05:53 PM
The Super Hooty Header Company just came out with a new helium filled titanium header that negates any point load problems in situations such as these. Might be worth a look-see. :)

i just ordered a stilleto from them:)

General nail bender
12-19-2007, 09:22 AM
The Super Hooty Header Company just came out with a new helium filled titanium header that negates any point load problems in situations such as these. Might be worth a look-see. :)

I just shop there for the wings

Bill Lacey
12-19-2007, 09:50 AM
Do they sell sky-hooks too? I've sold lumber to many jobs that could use a set of those.

parkwest
12-19-2007, 10:51 AM
I noticed in their catalog that their block stretcher still has the old canooche valve set up. On this guy's job he will need at least two block stretchers but I would hold off until they come out with the new valves. The new valves come with a lifetime warranty, I hear.

O'BrienConstruction
12-19-2007, 02:47 PM
You should visit there store, the second tuesday of every week they have specials on nailgun air.

James Eggert
12-20-2007, 09:04 AM
I'm so proud of you guys....not one bad comment!!!

Overbuilders
12-20-2007, 10:57 AM
This thread has quickly become my favorite and I have bookmarked it as such. Since it's inception, I find myself constantly checking for updates and new posts, rereading it in it's entirety every time I receive the email notification, as I glean more and more valuable information. This site is amazing! Youse guys are amazing! Merry Christmas to each and every one of youse! Burp.

parkwest
12-20-2007, 01:44 PM
What is truly impressive is what a bunch of geniuses can come up with to solve that man's challenge by networking like this.

Maybe we could all collaborate on a book based on this topic. I think we should call it, "How Big a Header do I need" based on our experiences with headers. It would sell millions. I'm thinking New Times Best Sellers List.

Dancing Dan
12-20-2007, 03:22 PM
I vote for "Don't Header Me, Bro."

oldschool
12-20-2007, 07:50 PM
To nail off to the kings and bypass using jacks, Simpson makes a special bracket just for that titanium helium-filled header. You get a bigger opening.

Toolwhore
12-20-2007, 08:35 PM
Are you guys messin' with me? I was serious!!!























LOL!!!!

mcocozzallc
12-20-2007, 09:22 PM
I vote for "Don't Header Me, Bro."

hahahahhahahahhahahahahahaha best qote of the year!


aahahhaha hysterical!

framer
12-21-2007, 03:26 PM
if this is an average house on slab, put in a 2-ply 11 7/8" LVL and i'm pretty sure you will be golden, unless you have some extreme point loads above. if you are on a wood floor, you have to make sure the cripples of the header sit on something solid....squash blocks, and maybe some additional columns.

dont listen to the guys that say hire an engineer... anyone with some common sense can get it done.

TWhite
12-21-2007, 04:46 PM
"don't listen to the guys that say hire an engineer... anyone with some common sense can get it done."

Thats why many here say hire an engineer. The OP is likely a homeowner.

O'BrienConstruction
12-21-2007, 06:38 PM
How does the house being on a slab dictate what the header needs to be? Thought loads and headers were based on whats above?

I'd check my local code book and if it covers my situation then I wouldn't sweat it, if it wasn't covered in my codebook I'd hire an engineer to say put this in and pay me $300 while your at it. You may have more common sense but I won't end up in court.

gdavis
12-21-2007, 07:34 PM
How's he going to end up in court. It's HIS house!

Roy:
They don't know how to answer you Roy, so they are f______ with you! :).

Just from your descriptions, chances of having a load that 2-2x10's can't carry over a span of 8' are pretty slim unless you have a wierd house.

If you have trusses, its probably not load bearing. If it is stick built you will have half the weight of the ceiling for the span carried each side. If there is no attic storage and the roof isn't propped up on this wall. Thats all the load which would be something like 1500 lbs dead load evenly distributed, or less. That's about 750 lbs per member or less than 100 lbs per foot. That's a pretty light load for a 2x10 spanning 8'.

Bottom line is that you are in the ball park.
Do it and if it sags too much come back and narrow the opening.
You won't need but one jack, long as it is nailed to the stud.

If your new header is truly carrying the end reaction of your ceiling joists, you biggest concern might be holding it up while you cut out and install the header. After that, nothing major can happen. So save your money. There was a lot of large structures built before they graduated the first engineer from a college.

Contrary to popular belief, the plywood isn't much help but if you have it on hand, toss it in, but I wouldn't buy a whole sheet for this header.

g

parkwest
12-21-2007, 08:02 PM
GEE! Out here we have to double the jacks on anything over 6' but if you say it isn't required that would save some lumber.

How much do you charge for structural engineering, anyway? Can I send our plans to you for your stamp of approval? I could save a few bucks there also.

And how DID they build those pyramids, anyhow?

O'BrienConstruction
12-21-2007, 08:04 PM
He won't on his own house, but the framer recommending this I'm assuming would do the same on a job he's hired to do.

gdavis
12-21-2007, 09:06 PM
parkwest:
I DIDN'T SAY IT WASN'T REQUIRED.
If you run the numbers on the jacks they won't come out the same as the code which is going to be very conservative.

A stud that is laterally supported will carry about 2000 pounds. So, you could have a header with about 4000 pounds on it and be OK with a jack on each end. I'd follow the code if I were doing it for someone else.

What our code is difficient on is the requirement for studs on each side of the opening. The code will only require one stud but if you are in a 130 mph wind zone, and you have an outside wall with a couple of 6 ft openings, that wall is getting pretty flimsy.

I know I'm playing loose with the numbers here, but that's about right.
I wouldn't use those numbers on anyone else's house without checking it more closely, but i'd do it on my own, and I would recommend that anyone else with some basic framing skills do it on their own home before they pay an engineer $300-500, to calculate it to 4 decimal places in about 5 minutes and then go up one size in case they missed a load in the rush.

And, I probably wouldn't get a building permit either. :)


Sorry, I don't mean to perpetuate the hijacking of this thread.

g

Don_P.
12-21-2007, 10:19 PM
The structural part doesn't scare me, but framing in stiletto's sounds mighty risky. I'm not trying that this year. Happy Holidays All!

TSJHD1
12-23-2007, 01:13 PM
One thing about forums, you have to discern the good advice from the bad. And know how to.
How's he going to end up in court. It's HIS house!

Roy:
They don't know how to answer you Roy, so they are f______ with you! :).

Just from your descriptions, chances of having a load that 2-2x10's can't carry over a span of 8' are pretty slim unless you have a wierd house.

Carrying it and carrying it without sagging over time (causing cracks just where everybody will see them) are two different things.


If you have trusses, its probably not load bearing. If it is stick built you will have half the weight of the ceiling for the span carried each side. If there is no attic storage and the roof isn't propped up on this wall. Thats all the load which would be something like 1500 lbs dead load evenly distributed, or less. That's about 750 lbs per member or less than 100 lbs per foot. That's a pretty light load for a 2x10 spanning 8'.

Bottom line is that you are in the ball park.
Do it and if it sags too much come back and narrow the opening.
You won't need but one jack, long as it is nailed to the stud.

If your new header is truly carrying the end reaction of your ceiling joists, you biggest concern might be holding it up while you cut out and install the header. After that, nothing major can happen. So save your money. There was a lot of large structures built before they graduated the first engineer from a college.

Contrary to popular belief, the plywood isn't much help but if you have it on hand, toss it in, but I wouldn't buy a whole sheet for this header.

g

Plywood is help. If it sags, as you mention, it probably won't happen all at once. It will happen after he's done the whole project. And, ever consider that if it does sag, and he REALLY wants an 8' opening, knowing that it would've sagged ahead of time, he would have opted for LVL instead?

One more reason why 2x10's are a bad choice here: As they shrink (and they will), they will cause gaps at the jacks. Then the ceiling will sag.

I think your advice isn't well thought out.

Tom

Toolwhore
12-23-2007, 01:52 PM
If you run the numbers on the jacks they won't come out the same as the code which is going to be very conservative.
A stud that is laterally supported will carry about 2000 pounds. So, you could have a header with about 4000 pounds on it and be OK with a jack on each end. I'd follow the code if I were doing it for someone else.

gdavis,

There is a slight flaw in your formula. Even though the laterally supported stud, as you call it (I'll call it a jack) is capable of carrying 2,000 lbs., on it's end grain, the contact surface on the header is on the side grain, which will crush, with that small of a bearing surface, causing drywall cracks, sagging ,etc. That is why 2 jacks are required by code on openings 6' and over, to increase the bearing surface and prevent this side grain crushing of the header. They actually do have good reasons for some of these codes, you know.

LET THERE BE LIGHT!!! :)

gdavis
12-23-2007, 07:24 PM
Well Tom, let's see your numbers. I didn't forget about the bearing load perpendicular to the grain but I think we are OK with that as well. But for a few dollars you could put in an extra jack. If you're going to slam my suggestion, show us the numbers.

I'll stand by what I said.

You referred to my -formula- as being flawed. What formula? Didn't use a formula. Didn't do any calculations. Its a no-brainer in this context. Would you hire an engineer if it was your house? Sure you'd hire one if you were building for someone else, but to make an 8' wide opening in an interior load bearing wall in your own house under the assumptions previously mentioned that would be extreme overkill.

I never suggested that everyone go around building like this. This man wanted to cut a hole in a wall in his own house-- and you're going to send him to an engineer? You can patch a lot of cracks for the cost of an engineer and there is a simple solution if problems occur-- shorten the span by adding a jack or two--- still cheaper.

So, get the chip off your shoulder and let's have a sensible dialog.

g

by the way Tom, if you fasten the dry wall near the bottom centerline of the header and let the corners float, the drywall will be much less likely to crack, if at all.

parkwest
12-23-2007, 07:42 PM
The guy comes on a professional forum to ask a question and now you say we should give him the same answer he could have gotten by going down to the bowling alley and asking the guys in the lounge???

TSJHD1
12-23-2007, 08:03 PM
You can patch a lot of cracks for the cost of an engineer and there is a simple solution if problems occur-- shorten the span by adding a jack or two--- still cheaper.

So, get the chip off your shoulder and let's have a sensible dialog.

g

by the way Tom, if you fasten the dry wall near the bottom centerline of the header and let the corners float, the drywall will be much less likely to crack, if at all.

Its not a simple solution. IF problems occur implies they'd occur after everything was completed. Its an 8'x3.5' opening, so its probably gonna have some sort of continuous sill. Just throw in another jack on each end doesn't take into account the extra work involved dealing with all the finish work.

As far as where to fasten the drywall, you think this guy knows that?

An engineer isn't needed, I'll agree, but your simplistic, you-can-easily-fix-it-later-with-some-more-wood-if-problems-occur advice ain't right either.

He needs to find a good contractor first off. And I think LVL is the way to ensure you won't have any lumber-movement related problems. With dimensional lumber what it is these days, and the nature of this kind of job (no time for the header to shrink before installing finishes), and the availability of engineered lumber (and the sizing charts too), its the best way to deal with large openings. I'd size it right to the necessary beam though. Meaning not just arbitrarily go with a pair of 11 7/8" LVL. Maybe one 7 1/4" with a 2x4 across the bottom would do it.

There.

Oh, this is just what our business needs too, btw: A professional on a construction forum telling a diy'er its not a big deal to do this sort of thing themself.

Tom

gdavis
12-23-2007, 08:29 PM
No... Here is how I saw it.

A guy (who probably isn't a professional builder) comes on the forum and he has a legitimate question. He shouldn't be here, but he is. Then several "professionals" begin to poke fun at him, laughning and amusing themselves. That doesn't leave the professional impression that we should leave, in my opinion. But several people gave him some recommendations including "you don't need an engineer" which I agree with.

The point I wanted to add was that its not rocket science, and you don't have to hire an engineer or even a carpenter, just use good common sense and proceed .... being careful to support the load when you cut out the hole (my only concern).

I used a few examples, shootin from the hip to try and put it in perspective.

I didn't give him a page of calculations, wasn't trying to be that specific. I was also not being careless... just suggesting that it probably didn't warrant hiring an engineer. I doubt he will even hire a carpenter and that would be OK too.

He should probably do what a lot of carpenters do -- using the code, experience in similar circumstances, etc. some calculations if they know how, then go up a size. They'd probably add another jack. And now we are back to what some here are suggesting in the first place.

To take it a step further..... so what if it sags. Some people would rather save $500 and have a sagging header. Alll headers sag a little. So what if it sags a little more than the code allows.

My advice was.. "you're close, use your judgement and proceed. You don't need to hire an engineer" My next statement would have been "but if you think you need to hire an engineer, use that money to beef it up instead."

And besides, the double top plate (there should be one) is going to carry about 25% of the load by itself and the load that the 2x10's will "see" will be plenty adequate.

More specifically to your question, Parkwest, I also don't think it is good for anyone here to give bad advice, but in the context of the original question and my answer, I don't think I was giving him bad advice. I thought it was pretty good advice and I still do.

And as far as the plywood is concerned, I would agree that the plywood will help. I didn't say it wouldn't . What i did say was "don't go out and buy a sheet of plywood just so you can put a 8' x 9.25" piece between the 2-2x10's. It isn't worth the cost of a sheet of plywood. And I mentioned it because there are many non-professionals out there who think that 2-2x's will hold up the moon if you sandwich in a piece of plywood.

(Now please don't anyone come back and argue about the weight of the moon.)

It's Christmas and I had a little time to drop by. I'm not here to stay.... don't have time for it. So, enjoy.

g

gdavis
12-23-2007, 08:44 PM
tom:

I think we're splitting hairs here Tom. I agree with your last statement and I addressed it in my response above to Parkwest.

In the context of my answer I don't think my advice was bad. I explained that above as well.

Now, are you aware that an LVL is going to creep as well and perhaps even more than dimensional lumber. It probably won't shrink as much as the 2x's but it will creep.

As for the other things like downplaying the work involved in trimming this opening. Again, in the context of my comments, I think that was appropriate. A diy'er isn'g going to get hung up on that. The mentality is that a Diy'er would rather do it twice than to pay someone to do it. ... and he'll improve his skills in the process.

Yeah, I get the point about making light of this, and I may have downplayed it a little too much to make my point..... which was, you don't need an engineer.

And Tom, a double 2x10 resting on a jack will have a surface area of 3"x1.5".
That is 4.5 square inches. Now what is the maximum stress in compression for a 2x10 No2 SYP or DF perpendicular to the grain in pounds per square inch? I'm sorry I don't have that committed to memory but you can check it if you want to and let us know how much it will hold.

So, why don't we just let it go.

Merry Christmas...... (and excuse me for not being politically correct.)

g

Oh. and if you're hung up that encouraging a diy'er to do this little job is going to be a problem for carpenters, you must be out of work.... that would be more a nuisance to me.... i would rather help a homeowner do it himself that have to deal with all the crap for such a small job. So there's the other side of that one. See ya.

parkwest
12-23-2007, 08:56 PM
The last thing you want to tell a diy'er is do what "feels" good.

Makes me think of the time a Diy'er's wife called us in on a remodel years ago. She wanted to know why her roof looked like it was sagging. They had decided to make the upstairs on a cape cod larger. Working weekends, the hubby had removed the kneewalls on both sides that supported the lap of the rafters for the whole roof. Luckily she called when she did. Hubby had now moved on to the next DIY'er project of removing the load-bearing wall between the kitchen and dining room to make it an "open area" LOL

TSJHD1
12-23-2007, 09:00 PM
g,

My problem with your advice is you oversimplified, made assumptions, and are treating this guy like he knows something about this sort of thing. And if he gets into a problem, he can just solve it by closing down his opening. I think you're being short-sighted, that's all.

And, other pros will also read this thread now, so the advice needs to be good enough for anyone, not just some DIY'er.

That's why I jumped in.

Another assumption you shouldn't be making is about the top plates. And claiming they help take load is a huge leap.

He said its a rancher I believe. Ever think it may have been framed with double top plates on exterior walls only, and single top plates on interiors? Lots of sog trussed ranchers are built that way. Ever heard of 94 1/4" studs?

He also said it was a load-bearing wall. Probably runs down the center of his house. Maybe does have 2 top plates. Maybe has a break in one right over his proposed opening. How much less ceiling joist load will the top plates be able to carry with a break in them?

I've seen too many people oversimplify even basic jobs. And I say that's exactly what you're doing. Yes, too many people over-engineer stuff as well, but the answer to that is not to do a job half-assed, with simplified advice from a forum.

Tom

TSJHD1
12-23-2007, 09:18 PM
Let it go???

Not when we have whatever you called Tom out on a few posts back still going on. Sensible dialog I think it was.

LVL creep? What the hell is that?

diy'er ok with doing it twice? How do you know??

Save $500? On what? I agreed an engineer isn't necessary. But getting a good contractor isn't an option.

Compression of 2x10's? Depends on load from above, just like Tom told you. And he mentioned the reason being its code. And you're telling this guy don't worry about that. One jack'll do just fine.

Me outta work? If you think that's where my comment came from you need to see the big picture for sure.

Every home show out there that makes our work look like anybody can do it hurts our business. It minimizes what we do. And anyone who sends out the same kind of message to a diy'er on a forum, in a small way does the same thing.

Don't want the hassle of a small job? Good thing all of us don't feel that way. Go make yourself a customer for life with that one. Get referrals. Do it right and probably even land a big job within a few years, without even having to competively bid against anyone.

Tom

gdavis
12-23-2007, 09:24 PM
Tom
The only one who knows what is really there is the homeowner who is looking at it, and he may not know. So we could speculate all day.

Again, my advice was not "since you probably have a double top plate, blah, blah, blah........" I never mentioned the top plate to him.

I'm trusting that this guy will take what he feels is appropriate caution for his own house, evaluate it with whatever ability he has and decide what he wants to do. My advice still stands..... "go for it". Your advice is different. There. He has a couple of opinions.

Worse case, If it falls down, what?. But it won't fall down if he uses two 2x10's and one jack under each end even though it MAY be a little substandard.

It will probably work just fine whether there is a single plate, double plate,or no plate.. But, if there is, it will help. You're making too much out of this. He could leave the header completely out (I'm not suggesting this to the homeowner, I'm talking to you.), and it wouldn't fall down.

So, argueing over whether he needs 2-2x12's instead of 2-2x10's or one or two jacks, is a small point when you compare it to the $500 plus dollars you'd spend if you hired an engeer and another $1000 to hire a contractor. Heck, if he has a brain at all at this point, he'll go with the 2x12's, wait 6 months for it dry out, verify it with a moisture meter, and box it in. .... or leave it unboxed and count his money.....

let's talk about something else.

g

gdavis
12-23-2007, 09:35 PM
OUr messages keep crossing...

you're going off the deep end Tom (THJHD1) ... the Tom that most of this was addressed to.

I'm done... rage on if you want.
g

BTW, unless they have rewritten the constituition and the General Statues in every state I'm aware of, getting a carpenter to do a job like this is always optional.

TSJHD1
12-23-2007, 09:40 PM
Thought you weren't staying. :)


Tom
The only one who knows what is really there is the homeowner who is looking at it, and he may not know. So we could speculate all day.

Again, my advice was not "since you probably have a double top plate, blah, blah, blah........" I never mentioned the top plate to him.

I'm trusting that this guy will take what he feels is appropriate caution for his own house, evaluate it with whatever ability he has and decide what he wants to do. My advice still stands..... "go for it". Your advice is different. There. He has a couple of opinions.

Worse case, If it falls down, what?. But it won't fall down if he uses two 2x10's and one jack under each end even though it MAY be a little substandard.

It will probably work just fine whether there is a single plate, double plate,or no plate.. But, if there is, it will help. You're making too much out of this. He could leave the header completely out (I'm not suggesting this to the homeowner, I'm talking to you.), and it wouldn't fall down.

So, argueing over whether he needs 2-2x12's instead of 2-2x10's or one or two jacks, is a small point when you compare it to the $500 plus dollars you'd spend if you hired an engeer and another $1000 to hire a contractor. Heck, if he has a brain at all at this point, he'll go with the 2x12's, wait 6 months for it dry out, verify it with a moisture meter, and box it in. .... or leave it unboxed and count his money.....

let's talk about something else.

g

We have given him opinions to evaluate, that's for sure.

Tom

Toolwhore
12-23-2007, 10:19 PM
Well I just got back from a very nice dinner, and I just can't help but laugh!! gdavis, I'm sorry you don't get it. I wasn't rude to you, just explained a fact in simple terms. Right now your attitude towards everybody here, plain old SUCKS. Merry Christmas!

TSJHD1
12-23-2007, 10:29 PM
Well I just got back from a very nice dinner, and I just can't help but laugh!! gdavis, I'm sorry you don't get it. I wasn't rude to you, just explained a fact in simple terms. Right now your attitude towards everybody here, plain old SUCKS. Merry Christmas!

I was beginning to wonder if it was me. :)

Tom

Toolwhore
12-23-2007, 10:36 PM
Hey there Tom. Your doing just fine. I hope he has a better day tomorrow, I'm just not feeling responsible for the misery he's going through today. NOT our problem! :)

mcocozzallc
12-24-2007, 04:35 PM
Let it go???


LVL creep? What the hell is that?

Tom

yeah, what the hell is LVL creep? Is that like the lvl that comes delivered in a
crummy lumberyard van with tear drop windows, cause the regular truck is in the shop? And then when you go to unload it the driver offers you candy?
That's kinda creepy to me. hahah

Is that "LVL Creep" driving that truck again?

Lavrans
12-24-2007, 05:03 PM
And then when you go to unload it the driver offers you candy?
That's kinda creepy to me. hahah

Is that "LVL Creep" driving that truck again?

Hey, is reads like there are some other "Uncle Shelby's ABZ" readers out there.

"K is for Kidnapper" See the nice man in the van? The nice man has some candy for you!"

gdavis
12-24-2007, 05:23 PM
Creep is something that occurs on the molecular level that causes a material to deflect (much later than the initial deflection) under a load over a long period of time. Also, When/if the load is removed the shape remains. It kinda flows like STP or other semi-solid, only slower. Lumber will do this but not as much unless it is heated up.

If you design a header over a garage door, especially a 19 ft opening, you can size the LVL to carry the load and meet deflection requirements but over time it will creep badly and deflect. So if this LVL is carrying the load of a brick veneer, you will surely have stair step cracking in the future unless you oversize it to some extent. I have understood that LVL's are worse than dimensional lumber when it comes to creep.

An LVL is probably not the best choice for a wide cased opening if dimensional lumber will suffice.

I try to make it a point to never size an LVL to the max for this reason.

I first learned of this from an engineer friend that works at an LVL factory. It has something to do with the elastic properties of the glue under load. While all LVL's under load will creep over 10 or 20 years, their biggest headache is wide garage door headers that are minimally sized or overloaded because the person that sized the header didn't know or otherwise account for the brick veneer.

glenn

Joe Carola
12-24-2007, 05:32 PM
Creep is something that occurs on the molecular level that causes a material to deflect (much later than the initial deflection) under a load over a long period of time. Also, When/if the load is removed the shape remains. It kinda flows like STP or other semi-solid, only slower. Lumber will do this but not as much unless it is heated up.

If you design a header over a garage door, especially a 19 ft opening, you can size the LVL to carry the load and meet deflection requirements but over time it will creep badly and deflect. So if this LVL is carrying the load of a brick veneer, you will surely have stair step cracking in the future unless you oversize it to some extent. I have understood that LVL's are worse than dimensional lumber when it comes to creep.

An LVL is probably not the best choice for a wide cased opening if dimensional lumber will suffice.

I try to make it a point to never size an LVL to the max for this reason.

I first learned of this from an engineer friend that works at an LVL factory. It has something to do with the elastic properties of the glue under load. While all LVL's under load will creep over 10 or 20 years, their biggest headache is wide garage door headers that are minimally sized or overloaded because the person that sized the header didn't know or otherwise account for the brick veneer.

glenn

Glenn

What does any header have in a opening have to do with brick? The brick sits on lentels. The headers carry no load of brick.

J.Buesking
12-24-2007, 10:16 PM
I think Glenn is way off the mark here.

I also think of that TLC song. So I creep yea...

http://www.youtube.com/watch?v=X0tNO3QFoOE

I've had a couple cold ones at the parents house tonight though.

Merry Christmas ya'll.

Kye GC
12-24-2007, 10:39 PM
I think Glenn is way off the mark here.

I also think of that TLC song. So I creep yea...

http://www.youtube.com/watch?v=X0tNO3QFoOE

I've had a couple cold ones at the parents house tonight though.

Merry Christmas ya'll.

I think this creep is a little more tasteful:

http://www.youtube.com/watch?v=nxpblnsJEWM

Kye

TSJHD1
12-24-2007, 10:45 PM
You're both wrong. http://www.youtube.com/watch?v=LGbO-nVBaFo

Tom

Kye GC
12-24-2007, 10:46 PM
Glen,

We've got this shakey house syndrome out here. When you feel it shake, you pray for over engineering.

Kye

always-learning
12-24-2007, 11:34 PM
I like STP's version better...

http://www.youtube.com/watch?v=Yh4-_-z0xAs

Kye GC
12-24-2007, 11:55 PM
I like STP's version better...

http://www.youtube.com/watch?v=Yh4-_-z0xAs

Isn't that Korn doing Radiohead

J.Buesking
12-25-2007, 11:30 AM
yea wow chuck that was a new one to me. I still like the video I posted better. ha

mcocozzallc
12-25-2007, 12:09 PM
honestly, has anyone besides glenn heard of creep?

O'BrienConstruction
12-25-2007, 06:54 PM
Let people keep talking about things like creep and we'll all be using steel i-beams for headers and discussing the best way to pad them out to except sheetrock and trim.

patrick
12-26-2007, 01:59 PM
Creep, yes I've heard of it. The failure that lead to the falling concrete panels in the Boston tunnel resulted from quick-set epoxy's tendency to creep. They should have used a normal-set epoxy for that application.

mcocozzallc
12-26-2007, 04:13 PM
howabout with lvl?