Help Sizing Beam

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Old 08-10-08, 11:53 AM
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Question Help Sizing Beam

I would like to replace a load bearing wall in my basement with a beam and need some help sizing the beam. The span is 19' and the distance on one side is 12' and the other side is 7' which gives me a total tributary width of 9'. The space above is a living room with hardwood floors. The house has 2 stories above the basement, but this span is only supporting the one floor above. I was thinking I would use LVL's, but am open to other suggestions. The living room above has the exact same span condition with a beam spanning the same distance to support the top floor and that beam isn't any thicker than 3.5", but it is encased in drywall and I don't know what it is made of. Since I would be duplicating this in the basement I would assume I could get by with (2) 18" deep LVL's, but would like to know for sure.

Any help would be greatly appreciated.

Thanks,
Paul
 
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Old 08-10-08, 02:03 PM
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Help Sizing Beam

Get an engineer to save you some money.

He will also be able to give you a design for the footings under the bearing points for the beam. the wall you are replacing probably does not have a proper footing for the load the beam will be carrying (LL + DL).

Even if you do it yourself without a permit, you will have a design to show the future purchaser that it was not just a "patch job".

Dick
 
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Old 08-10-08, 02:04 PM
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Please check Calc's

I think I found my answer here http://www.rfpco.com/pdfs/EWP_DG/Lvl.pdf
According to their instructions and tables, I have to use a longer tributary length because my I-Joists are continuous so the calculations are 50PSF x 12.25 x 1.25 which gives me a total PLF load of 766 and a 2-ply 18" LVL will span my 19' distance.

I would really appreciate it if someone can tell me if I did this right though.

Thanks,
Paul
 
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Old 08-11-08, 04:27 PM
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first, (2) 18" lvl's won't make that span according to those tables and the load information you provided. The same is true for my software. (3) 16" lvl's will work--according to your numbers.

BUT you need someone to verify that those numbers are sufficient to suit your situation; to make sure there isn't anything else going on underneath the surface that you haven't picked up on. This is a big project, also probably not a diy.

And as previously mentioned you'll need footings under the bearing points, because there will be nearly 7500 lbs. coming down off each end of that beam.
 
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Old 08-12-08, 06:37 AM
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The biggest point not to miss here is what the other two guys said above....766plf over 19' = 7,277lbs on each support at the ends. The load-bearing wall distributes the 14,000+ load across it's length and any basement slab will easibly support that being transferred through the bottom plate....but it's a different story when that becomes a point load on the ends.
 
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Old 08-12-08, 06:51 AM
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Change of Plans

Rather than replacing the wall with a single beam, I've decided to do it in smaller 6' segments so I'll have several columns. This will make it a lot more manageable for me to do it myself, save some money and alleviate the footing problem. There is already one 6' opening and I can do the other two one at a time to minimize the temporary bracing.

Thanks for all the replies.
 
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