Extending header

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Old 03-01-09, 09:40 AM
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Extending header

I currently have a double 2x12 ceiling header that spans 18ft. Single story house, this header runs down the middle
(actually off-center) of the house and supports 2x6 joists that are 12ft on one side, and 16ft on the other. Roof is rafter - not trusses.

I'd like to extend the header 3 more feet for a total of 21 feet. Can I do that by sandwiching two 21 foot 2x12's on the sides of the existing 18 foot header? Or will I need to have the 18 footer removed, and a new 21 footer installed? Are 2 2x12's enough to support a 21 foot span?

Thanks
 
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Old 03-03-09, 12:14 AM
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As long as you sandwich the existing header with 2 21'ers and fill in the rest of the space with 2 3' 2x12 that will support what you need. In the end you will ultimately have a header that is 4 2x12s 21' long. That will support a hell of alot of weight.
 
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Old 03-03-09, 04:52 AM
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Not sure where you live, but let us know where you find 21' 2x12's. I'd be interested to know. You can get LVL cut any length you want up to 53'. Is this beam exposed to the underside of the ceiling joists? Do they rest on it or are they attached to the side of it? Just trying to get a visual on what you are doing.
 
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Old 03-03-09, 06:46 AM
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Originally Posted by chandler View Post
Not sure where you live, but let us know where you find 21' 2x12's. I'd be interested to know. You can get LVL cut any length you want up to 53'. Is this beam exposed to the underside of the ceiling joists? Do they rest on it or are they attached to the side of it? Just trying to get a visual on what you are doing.
The ceiling joists sit on top of the current double 2x12 beam. I was considering 2x12 I-Joists to sandwich on the sides - but maybe LVL is a better option?

Thanks for your help
 
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Old 03-03-09, 05:56 PM
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Well, the LVL will have solid sides that you can finish with sheetrock, etc. where the I-joists are indented.
 
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Old 03-04-09, 07:27 AM
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So 2 2x12 LVL's or I-joists will be adequate to support a 21 foot span of ceiling joists correct? I can either replace the exisiting 18 footer, or sandwich the 21 footers on the sides of it.
Another question - is there any way this beam could be put ABOVE the ceiling joists? Are there hangers of some sort that could adequately support the ceiling joists hanging below the header? Be nice to have a flat ceiling.

The existing joists overlap on top of the existing beam, and are nailed together which I assume is the structural bottom of the roof triangle so I don't think sawing a gap in them and dropping the beam in there and attaching side joist hangers is an option.
 
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Old 03-04-09, 09:37 AM
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I was going to suggest going overhead, but didn't know how ambitious you wanted to get. Plus the problem of getting the header up there. If you can get it into place I'm sure there are hangers that will attach it to the joists. I have never done it, but have had to climb around a couple in my days. Much nicer end job.

Bud
 
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Old 03-05-09, 01:07 PM
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Originally Posted by Bud9051 View Post
I was going to suggest going overhead, but didn't know how ambitious you wanted to get. Plus the problem of getting the header up there. If you can get it into place I'm sure there are hangers that will attach it to the joists. I have never done it, but have had to climb around a couple in my days. Much nicer end job.

Bud
About placing the beam above the ceiling joists: How about I site-build a header out of 12' 2x4's or 2x6's on top of the joists? Stagger the ends and glue and nail to create the beam right there in the attic? Would that work? Still need to know what kind of hangers might be appropriate.

Thanks
 
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Old 03-05-09, 03:07 PM
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Whoa, we were talking about 2x12's now you want 2x4's or 6's. Just kidding, I'm sure you had something more in mind than single laminated 2x4's .

Yes you can build up a header in the attic out of 12' boards, but go four wide, with 1/2" plywood stagered between the 2x12's. It may sound like overkill, but you dropped to 12' boards and will need to compensate for the joints and 21' is a H*** of a long span. Now, remember that all of this weight will be carrier on the two ends, so you don't want a couple of 2x4's down there trying to hold everything up.

Some long roof straps or angle fabricated to go under and over should work fine. I can detail something if needed.

Bud
 
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Old 03-05-09, 03:32 PM
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Originally Posted by Bud9051 View Post
Whoa, we were talking about 2x12's now you want 2x4's or 6's. Just kidding, I'm sure you had something more in mind than single laminated 2x4's .

Yes you can build up a header in the attic out of 12' boards, but go four wide, with 1/2" plywood stagered between the 2x12's. It may sound like overkill, but you dropped to 12' boards and will need to compensate for the joints and 21' is a H*** of a long span. Now, remember that all of this weight will be carrier on the two ends, so you don't want a couple of 2x4's down there trying to hold everything up.

Some long roof straps or angle fabricated to go under and over should work fine. I can detail something if needed.

Bud
Right no - I was talking about building a beam out of 2x4'x laying flat, and stacking them to 10 or 12 inches tall to create a 3.5" x 12" beam that is 21 feet long. I've heard of that being done.
And right - would plan on having triple or quad jack studs supporting the ends.
thanks
 
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Old 03-05-09, 04:15 PM
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The vertically stacked ones are more for appearance, which obviously doesn't matter, and much more dependent upon glue and technique for strength. I have built the three wide and four wide versions as described with osb layered in between and you could move mountains with them. In your case, the loading isn't that bad so the three wide would probably be enough. Just not two wide with the 12' boards.

Something you will have to guess on or shim afterwords will be any deflection in the new beam. I usually build them with a touch of crown as I know under load they will always give a bit.

Also, make sure there is matching support in the basement. Sounds like you can handle it from here, good luck,
Bud
 
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Old 03-19-09, 07:33 AM
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Follow-up: Found some nice load/span tables here http://ilevel.com/literature/tj-9000.pdf I ended up using triple 2x12 (1-3/4 x 11-7/8) LVL's under the ceiling. Ordered the LVL's at the HD and they were ready to pick up the next day. Put them in one at a time and nailed together. Easier to handle than one big beam.
 
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Old 03-19-09, 09:12 AM
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Sounds like you did a good job. Right hand salute, left hand under right elbow, push gently and pat yourself on the back

Bud
 
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Old 10-01-09, 11:58 AM
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Please help?

me too: I want to place a beam ABOVE the joists in a single story home in the midwest (some snow and ice). I have never done anything like this tho, never seen it, can't find any pics of it and only heard it once or twice: I'm a bit leery

The resulting span would be 18 ft. Joists are 2X8s. Right now there is a loadbearing wall with a 2-2x4 top plate, joists overlap on top of this wall and run 11ft on one side, 19ft on the other.

I'm thinking 4-2x12s glued and nailed with hangers of Simpson twist straps (TS18s, 4 per joist, 2 on each side of beam), leaving the top plate in place and blocking around it to the support beam. 6x6 or 4" round steel columns would fall directly over one of the main support beams in the crawl.

Sound ok?
 
 

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