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Discussion Starter · #1 ·
I need some help from someone that understands the math better than I do. I am adding a dining room and will be removing a load bearing wall between the living room and the new dining room.

I need help calculating what size beam, what type to use, and if the I beam I already have will work.
The unsupported span is 15'. I live in north Arkansas with a ground snow load of around 20lbs.

I have an I beam that was given to me that is 19' long and is s10 x 23.5. As best as I can tell it is 23.5 lbs per foot anyway but when I look online the closest beam to that is s10 x 25.4.

My question is this, will this beam support my 15' span or do I need something else and what would that be, LVL or different I beam.

Thanks for any help.
Brian
 

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JOATMON
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You need a structural engineer for this.
^^ Ditto^^

There is more to this than just a 'beam'.

Do you have the footing under the walls where you are putting the posts for the I-beam to support the point loading?

And as with any project of this type, you will need a permit.

I've seen people pick the right size beam...but the footing under the beam posts couldn't handle the extra weight and it caused major issues.
 

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Discussion Starter · #4 ·
Thanks for the reply guys. I have been looking for a structural engineer but I live in rural Arkansas and as of yet have not found one within 70 miles. I do plan to talk to one first though but Im just trying get an idea now.

As for a permit, not in rural Arkansas.

As for a footing, the wall that i will be removing is currently an external wall that is supported by a full length block footing.

My gut feeling is the steal I beam is overkill so I think I will look into an LVL header. After all, my load and span really aren't any different that a garage door opening would be.

thanks
 

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I have gas!
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Your local lumberyard that sells LVL may be able to help you spec the beam. You need to go in with the knowledge of what loads and types of load there is above the beam and measurements of that load such as the tributary loads above it.
Also, as mentioned above, make sure that you follow the load to the foundation to make sure that you don't put a point load on another beam.
 

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Civil Engineer
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I am curious what makes you think you have an S10x23.5 beam? In my experience, steel beams are rarely marked, you only know what size you have by carefully measuring all the relevant properties, then matching the beam up with a steel manual. Unless of course you purchased the beam from a steel yard, they would know what size you bought.

The currently manufactured steel beams that are close to what you say you have is a W10x22, or an S10x25.4. The numbering on steel beams works this way. The first number, 10 in this case, is the nominal depth in inches. The second number is the weight in pounds per foot of beam. The flange width, flange thickness, and web thickness are found on steel charts.

There are obsolete shapes going all the back to the early 1900's that have different sizes than current, similar shapes. You need to look at historical documents to determine the beam type you have, if it is more than about 40 years old.

One other detail is that the strength of the beam depends on the geometry of the beam, plus the strength of the steel. Modern steel beams are typical A36 steel, sometimes A60 steel, which tells you the yield strength of the steel. Older beams often used lower strength steel, so you really need to know exactly what you have before you begin to do calculations.

As to getting someone on an on line chat forum to determine if the particular beam you have is suitable for your specific application, that could be problematical. The folks on this forum who are capable of doing the calculations correctly may be professional engineers (like me), and are prohibited by law from doing engineering work without seeing the site, and having a contract. So the only folks on this forum who would consider offering an opinion are probably not legally qualified to offer a definitive opinion. So what exactly would you do with an internet opinion from someone you never met, who has never seen the site, and likely lacks the required qualifications to legally design your project?

Since you are in rural Arkansas, and may be unable to find a qualified professional, your best bet may be to go to a real lumberyard with your house framing plans, and let them size an LVL for you. A lot of the time a real lumberyard has an on call engineer who can size the beam, and stamp the plans (apparently not necessary in your case). The lumberyard simply rolls the cost of the design into the beam price.

You still need some help with the footing design and supports for the beam. Perhaps the lumberyard can help you out with those issues as well.

As for the installation process, be very careful to make sure you have adequate temporary support for the joists above during the install, improper temporary support can lead to collapse of the house. Best to have someone helping who has done this before, and understands exactly how to do the job safely.
 

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Discussion Starter · #7 ·
Daniel, thanks for the info and recommendations.

Really, what I would most like to know is what load the s10 X 23.5 I beam is capable of. After reading your comments I realize now that this beam IS FOR SURE over 40 years old. I am calling it an s10 because it has a nominal depth of 10 inches. The flange width is 4.5" so when I looked up current common beams it more closely matched standard beams than wide flange beams. I got the 23.5 by weighing a one foot piece. The beam was twenty feet originally and I cut a foot off it and weighed it. As another check, I entered all the measurements into Ames Sectional Properties Calculator - I Beam and it told me it should have a mass of 377 lbs and when I multiply 23.5 by 16' I get 376 lbs. I would say that is pretty close.


As far as for the header in this project, I have decided to use LVL and talk to my lumberyard to see if they have an engineer that can help with the sizing. The load is actually fairly minimal.
The rafter span that will top load it is 12' on one side and only 4' on the other. We do have a very good local lumber yard that sells a lot of LVLs that I am sure will be able to help me.
 
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