need clear span framing help

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  #1  
Old 07-12-09, 11:05 AM
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need clear span framing help

can someone please help mew with the question/picture?
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  #2  
Old 07-12-09, 11:51 AM
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Not sure if this is what you are looking for, but a single 2x6 will span a clear 12' 9", so your set up is over kill, but more than adequate. Not knowing what you are planning puts us behing the 8 ball. Is this on a slab, framed basement/crawl. Wherever your vertical supports are to be placed, there must be "carrier" support to the foundation. What type weight are you talking about? Is it load bearing?
Georgia's the largest state east of the Mississippi, so where are you located?
Oh, yeah, you may want this reference Maximum Span Calculator for Joists & Rafters
 
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Old 07-12-09, 12:21 PM
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its on a slab, i just want to make sure that the married 2x10's can support half that ceiling and half the simple roof from the center of the room towards the perimeter wall. the 2x10's have a 2x4 wall under them that runs directly under them. i want to take a 9'3" section out of the 2x4 wall. does this sound better?
 
  #4  
Old 07-12-09, 04:22 PM
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Both your ceiling joists and rafters are over-spanned by 3' - or 33% loaded more than they should be. I would contact your local Building Department for information. Be safe, G
 
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Old 07-12-09, 04:50 PM
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Do you have trusses or are your joist/rafter systems stick built like you have described? Are you planning on taking out part under the 2x10's, or in the 12' span. If the latter, you can't do it, as G has stated the span is too much for just 2x4's
 
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Old 07-12-09, 05:08 PM
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YES! i want to take out part of the wall thats under the 2x10's. i think they should be plenty strong as long as the ends are properly supported. please egt back to me asap. im in a holding pattern...
 
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Old 07-12-09, 05:59 PM
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chandler- stick built and yes, under the 2x10's......
 
  #8  
Old 07-13-09, 07:57 AM
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Originally Posted by GBR in WA View Post
Both your ceiling joists and rafters are over-spanned by 3' - or 33% loaded more than they should be. I would contact your local Building Department for information. Be safe, G
How was this determined? From his original drawing he give the center rise but not the run. From the drawing, one could probably carry out the calculations with math. Is that what you did, to determine the overall lengths?

nut,

Why are 2 x 10's under the center, if there is a wall there. The original full wall alone shoud have been only necessary to carry the weight.

And remember that the weight is primaily for carring the celing. And even some of that weight is being transfered out to the outer wallls via the roof trusses and the vertical support boards. A roof, relies on the outer walls, and the joist being used as a giant tie, to keep the walls from bulging out, under roof load. However, that joist, if a truss is to free span, must be heavily gang nailed and/or gusseted together in the middle. If it is not, and there is simply a broken joint where aay they just butt together there in the middle, then you truly would have to really rely on a beam or wall under it for support, more.

I read this post this morning, and quickly responded, based on basic knowledge I have. And would be glad to discuss this more when I get more time, as I have to go to work, repairing this and that.

I understand what you are trying to create. But I do not get how those beams already got there, and why. Even though I understand why you think they need to go there.

I am thinking there may be another way to carry that, or share carrying the load for the planned 9'-3" span. You could go into the attic and add a 2 x carrying board stood on it's edge and secure it to the 3'-9" vertical supports. You would probably need a 2 x10" x 12' to secure this to about 5 of the center-of-truss vertical boards. Those carrying board would be directly above the 2 x 10 beam below.

You would have to double up though on the existing 3'-9" vertical supports so that each one extends to the top of the rafter and to the bottom of the joist, and be securely fastened. Then nail or screw that 2 x 10 on edge, up against all those vertcial supports.

Another way to increase strength, out of a given size header, is to sandwich a steel plate, rather than 1/2 inch plywood, in it, to create a "flitch plate beam". I am sure you can read about such beams on the net. I have worked with and made them in house building, to carry bigger spans. They were actually put into the blueprint -not just my doing, for the heck of it. And when using such a beam, when you know there will be a great load, you also should double up on the jack studs so that you have 2 rather than one jack stud (3 studs in all counting the full length king stud, so you have 3 inches that the beam is sitting on.

[I am not an architect, even though I tried to pretend I was one 25 years ago, for what that is worth, in building and remodeling, where I built from scratch or gut and add things, etc.]
 
  #9  
Old 07-13-09, 12:15 PM
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The span is in green, both the joists and rafters, 12'. IRC... 2x4, 16"o.c.= 8'9" span
ceiling joist. Roof rafter- 2x4, 16"o.c.= 8'11" span UBC says no to 2x4.

Single Family Residential Construction Guide -

All the load is on the rafters, these are not trusses. 24' total span /2=12' load center wall is carrying. Roof load of 20#live load + 10# dead load = 30# times 12' span = 360# per lin.ft. on the beam/wall. 360# times 9'3" = 3330#

Drywall on ceiling joists = 10# load per ft. times 12' = 120# per ft. times 9'3"= 1110#

3330# +1110# = 4440# load on beam depends on what species the 2x10's are as to how much weight that they are rated to carry. 2-#2 wood 2x10's will span 7'10" carrying roof and ceiling w. a 30# ground snow load. 2-#2 wood 2x12's will span 9'1" w. same snow. Be safe, G
 
  #10  
Old 07-15-09, 11:09 AM
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THANKS! luckily in georgia we dont have snow. i already removed the wall and we are good to go. no issues. fully supported, no snow. thanks guys.
 
  #11  
Old 07-16-09, 05:57 AM
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So what did you do, carpentry wise?

I did learn something along time ago, that rather fascinated me. When you know nothing you presume that removing the wrong board here or there will cause utter and instant collapse. Usually not so. If you nail enough boards, lath, sheathing, siding, etc., together - it turns out that even if structural members are removed, that the structure still stands. However, over time, if the support was indeed needed in that location, it will sag gradually over time as fasteners try to bend and or the wood itself sags, and/or other sturctural components try to twist or buckle.
 
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