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20 foot span with triple 2x12 beam, possible or rediculous?

20 foot span with triple 2x12 beam, possible or rediculous?


  #1  
Old 11-24-17, 08:49 PM
R
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Post 20 foot span with triple 2x12 beam, possible or rediculous?

Hello, new member. Looking for a bit of help.

I am redoing my kitchen and I want to remove a bearing wall. And replace with a 2x12 beam. The length of the span is approximately 20 feet, I have four 24' 2 x 12's. The room is 20' wide from outside wall to outside wall.underneath is a basement with a beam directly below the wall in question, the beam is a 6x6 timber supported every 8' by 6x6 timber columns. Above the wall is unfinished attic space. 2x6 rafters 16 on center. The roof is a 12/12 pitch(has recently had 3 layers of shingles, and a layer of cedar shake removed, a new 3/8th inch deck, ice and water, felt and architectural shingles. Gable roof 2x4 construction 24 on center. All existing structure is typical of 1910 construction practices and this area of the house was an addition probably done circa 1920 to 1940. 2 x4s measure 2x4 and so on.

My concern is whether I can run the entire span with only supporting the beam at the 2 ends and a third support 3 feet from one end. And I hope to add living space in the attic at some point, bedroom only in this area.
 
  #2  
Old 11-25-17, 03:54 AM
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You say the wall you are removing is structural and there is unfinished attic space above. What is the wall supporting? Is it carrying a roof load?

The next big issue is with the beam down in the basement. You will be going from the load being spread out continuously along the basement beam to putting the load on two concentrated locations. At the minimum you'd probably need columns directly under the load bearing points which may require the addition of footers and columns.
 
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Old 11-25-17, 07:42 AM
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This is something for an Architect, 20' is a very long span. You will most likely need to install an LVL beam, maybe even doubled up.
It also matters how the ceiling joists/rafters will be connected to the beam.
Like PD said you will probably need new footings and posts at the beam ends. You are taking 20' of spread out load and moving it to only 2 bearing points that might only measure 3.5" square.
 
 

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