Header Sizing

[Cozmic Wireman]

Need help sizing a header for a garage. Header will free span 24 feet over the garage door, and will support the ceiling and roof only. Roof pitch will be 4/12, if that makes any difference in loading. The ZIP is 21239 is that helps with anything related to snow load. I'm alright with using steel or a lam beam, but I don't know what size of each to look at so that I can price it out. It would be nice to know how much the header has to bear on at each end too.

[Wgoodrich]

You are off the charts of the IRC requiring you to contact an engineer using an engineered product. Have that engineer give you the answer in writing to hold him or her liable if failure occurs.

Good LUck

Wg

[Cozmic Wireman]

I did notice that the code stopped at 18 feet. There should be other charts available. I am fairly certain the the engineer isn't going to break out a slide rule to give me the answer. He's going to reference a chart of some sort. I know that these lam beam come in great depths, and steel is almost infinate. Surely someone publishes performance data for this stuff.

[suemarkp]

What else holds up that roof -- just the opposite wall? If so, what is the distance from front wall to back wall. This will provide the total load that must be supported at each end. What city are you in (I'm too lazy to look up the zip code).

[Cozmic Wireman]

Just the opposite wall holds the roof up. The room is a 24 foot square, so the opposite wall is 24 feet away. The front roof is a 4/12 pitch, and the back roof is a 12/12 pitch. The ridge of the roof is offset pretty far toward the back wall. I live in Baltimore, MD.

[suemarkp]

I can go do a calculation if you want, but off the top of my head this is looking rather large. I'm guessing that something like a wood 4x16 or 4x18 is what you need. Do you have the height for something this big? Is there any way you can live with a more normal door or two 10 foot doors?

I don't know how to calculate steel, but that would probably be smaller. My garage is 24' deep and the header is 17' wide. However, it holds up a floor and a roof. It is a 4x12 (really 3.75 x 11.75) douglas fir.

[Cozmic Wireman]

Well, in my case, the door is already being manufactured. I'm housing a light aircraft in there, and the width is needed.

[Wgoodrich]

An engineer will calculate the pounds per square foot load that is applied to this header. Then he will use charts that have modules of elasticity and fiber bending for that amount of weight using each species of lumber of grade of steel or of manufactured wood. This is his job and what he or she is trained to do. You have no qualifications to do anything that is not shown on the charts of the IRC per IRC rules. If you go off the charts you are required an engineered product backed by a licensed engineer.

Doing anything different would put your liability risk up there pretty high not worth the risk. Do not be afraid of an engineer doing your calculations and telling you what you need. Often times this cost factor is less than a couple hundred and sometimes much less all depends on the difficulty of the calculations and liability they must assume in their service.

Be safe

Do it right.

Wg

[Cozmic Wireman]

Some might say that an electrician should only do electrical work, and the homeowner is not qualified to do so. We all know that is not true in many cases. All I asked for was the same information the the engineer would otherwise use to make his calculation. I suppose my mistake was posting this question in the building code forum. It might have been better suited in another forum, since I already know that this is off the charts according to the code. Mr. Goodrich- don't underestimate the skill or the ability of anyone. You'd be selling a lot of people very short. For crying out loud, it's the American way.

[Wgoodrich]

I often deal with many that are dead set they know when they don't know. I gave you the method of calculation the engineer will be using with no glorifying. I gave you what you seek. I also felt need to warn you this is something a layman should not be doing. While it is true laymen do it all the time they often do not realize the risk involved.

Just for example a 20 pound snow load with a ceiling of 10 pound live load rating considering a 24' x 16' span would be about a total of 11,520 pounds sitting on that header.

Then per the IRC headers 4-2x12 header carrying a 20 pound snow load and a 10 pound ceiling load would have a maximum span capability by the Code 12' 2". The Code goes no further spans than that for this scenerio because they are wanting you to go to an engineer to keep it safe.

That header snaps and a lot of pounds can land on anyone's head not to mention a very expensive plane. I would say that is a life safety issue dictating the need of warning for safety.

My comments were not meant to irritate you but to protect both of us. [you and me] in this post and replies.

Sorry if I offended you but I did what I felt was required of me considering the situation.

My opology expressed

Wg

[Hatter]

Looking for a chart... here you go:
http://www.wii.com/StrucLam.pdf
You will have to do some calculating though. Just for a jumping off point for you - I am working on something right now, a two story addition and for a 23'6" span I am using 18" LVL 3ply(I think) and in steel I was told to use w8x35. If you do it in steel though, you are going to need a lot of help lifting it.- I would suggest the LVL
Good Luck

[scuba_dave]

When I discussed my garage/addition (attached) with my architect he said he would run the finished plans by an engineer for final approval
I will have a garage 25' x 36' deep, with (2) garage doors. I'm planning on a single beam running down the middle 24' to the 1st support beam, then another 12' to the back wall. I've always hated those support beams right where you park your car.
Above the garage will be a 25' x 36' great room. Then above the front 24' of the additon will be a "3rd" floor for storage - 24' x 24'
My interest in specifications is to make sure this is built ABOVE code for me.
My wife wants a pool table in the front nearthe garage doors. And I have plans for a saltwater fish tank atthe back of the great room - possibly as large as 500 gallons.
I have told my architect all of this, but I like to be sure & double check.

[Wgoodrich]

If you don't have formal schooling on how to do the calculations your best bet is rely on your archetect that you chose with the engineer he or she is asking for back up on the calculated load. All you mentioned applies to the design load of this building creating data used to size your support beams. What you are discribing is more complex needing support of an engineer in the calculations. We could provide what we would calculate but you have some heavy living loads added to normal live and dead loads already getting complicated. I suggest your best bet is having trust in the licensed archetect and engineer involved. Sounds like your archetect already recognizes the complexity of your needs when stating approach to an engineer for calculations. That is the proper method of action. YOu are on the right track.

Good Luck and let us know how you come out.

Wg

[2cpus4me]

I often deal with many that are dead set they know when they don't know. I gave you the method of calculation the engineer will be using with no glorifying. I gave you what you seek. I also felt need to warn you this is something a layman should not be doing. While it is true laymen do it all the time they often do not realize the risk involved.

Just for example a 20 pound snow load with a ceiling of 10 pound live load rating considering a 24' x 16' span would be about a total of 11,520 pounds sitting on that header.

Then per the IRC headers 4-2x12 header carrying a 20 pound snow load and a 10 pound ceiling load would have a maximum span capability by the Code 12' 2". The Code goes no further spans than that for this scenerio because they are wanting you to go to an engineer to keep it safe...
Wg

24' clear spans require steel or an engineered product. The 20 pound snow load is part of live load. It needs to be assessed for both live and dead loads. 20lbs is a pretty light snow load, by the way.

Say the structure is 24x24, and half of the roof weight is bearing on the side wall he wants the 'header' put in. Using your 20lb live load and 10lb dead load values for the structure means there is 12*20=240(live) + 12*10=120(dead) load per foot pressing down on the beam in uniform fashion. Almost 9000 pounds total.

If that gets plugged in to the steel sizer (beamchek software), it says a W12x19 hunk of steel may work. That beam is 4" wide and 12" deep and weighs 19lbs/foot (500lbs total). It will also sag about 3/4" under full load, and 1/4" under normal conditions. That is about the smallest steel wide flange beam that could be used and it would have to be verified by an architect. There are lots of bigger beams that will work, too, and the Engineers will likely use the beamchek software to size them for you.

2cpus4me