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Discussion Starter #1
I am a few weeks away from basement footings starting. I spoke with my framing contractor a while back and asked him about my idea to use a lvl beam to support a portion of the main floor in the basement. The depth of the house is going to be 30 feet, & I will have 11 in 7/8 inch i-joists making that span. I believe they are rated for 16 foot spans with no needed support if I remember correctly. I want to have a an open area in the basement that would be 20 to 24 foot distance without any middle support wall. The rest of the basement will have a 2x6 support wall down the middle.

I was told for every foot I need to support, I need to account for one inch of lvl depth, or height technically. If I throw a post in the middle, that would divide the lvl height required in half, right?
 

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Nope. Unortuneatly it is not that easy as a 12" deep LVL is 4 times (not twice) as strong as a 6" LVL of the same thickness. If my memory is correct.
 

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Discussion Starter #5
The basement is 9' deep or 8''8" after the floor. The load above this area is just the floor and a live load of people. No load bearing walls are in the middle upstairs. I can get a basement outline up later. HVAC and plumbing will be running above the lvl beam between joists. I may have HVAC run along the beam with a baffle, that will be the HVAC guys decision. The area I want to support is on the north end of the house. A nice family room area of 20'-24' wide x 30' deep. depending on the lvl support....it may run right down the middle with one or two vertical posts to support it. My two main concerns are where will the concrete footings in the floor need to be, and how many vertical supports for the lvl will be needed.
 

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Presumably there is a design for the house, which you are now planning to change. You need to get the designer (architect or engineer) to redesign the framing. If this is a stock set of plans you are building off, you may need to hire an architect or engineer to redesign your framing. This is an internet chat forum, probably not the best place to be getting structural design advice for arguably the most important framing member in your house.
 

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Discussion Starter #7 (Edited)
After looking at Gary's link it seems 18" is required. I am sure there are different LVL's per material. So now....does adding a vertical support reduce the thickness needed? I would not mind one support column.

@Daniel I think my framing will be staying the same. It's a difference between an open 20x30 area in the basement or having a support wall with some headers down the middle of the entire basement and having it be more like 2 rooms instead.
 

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I would use a steel beam for that situation. An 18 inch lvl below the joists will feel really low. I bet a properly sized 12" beam would probably suffice. A lot of times the steel supplier can engineer the beam for you. Cost will also be similar.
 

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Are you trying to build a Home Theater? If you are, there are guys over at avsforum.com that do this kind of stuff for a living. As for the wide open space. If the house is built, you are going to have to consult with an architect to get plans drawn up, for the change, so you submit the proper permits.
 

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Let me give you a little insight on what happened when they built the Crowne Plaza here in Springfield, IL. They wanted a very large Ballroom on the 2nd floor, that would not need any poles or walls for Load support when they built the hotel. The convention space on the first floor was a little different.

When came down to being done and over. The I Beam they used, was at least 6'-7' high, and about 4' wide for the horizontal members. All for the large span they needed. This change was made while the hotel was still in the stage of putting in footers to support the first to third level Steel frame.

Since you are still in the preliminary phase. I can tell you that your GC and the crew may get a little Po'd if this change is made after they pour the slab for the basement floor. Hope you are good at getting a case of 12 year old Glenlivet Whiskey. Or willing to buy them dinner at the local steak house.

I really do not care what line of work you are in. When you get presented changes half way through the job, or after you have done everything. Tools are known to go flying across a room.

Also remember the more changes you make, the longer it will take, the slower the crews will work, the more corners that will be cut. Then add in the fact that they will be wanting more money, because you made a change during the middle of the pre-build.
 

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Discussion Starter #12
Well I made this choice before concrete because I know the columns will need a foundation below the basement slab.

Luckily I am the main builder hiring sub's for the jobs.
 
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