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StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 7144
Experience:  Structural Engineer
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What size steel beam would I need to span 33 feet I want

Customer Question

What size steel beam would I need to span 33 feet
I want to get rid of the 3 lally columns in the basement
Ranch stye home roof ridge line directly over this basement beam
Take into consideration we may be adding a second-floor in the future
The front to back width of home is 28 feet
Submitted: 2 years ago.
Category: Structural Engineering
Expert:  StructuralEng replied 2 years ago.
Will the beam support any ceramic tile? The beam is going to be large.
Customer: replied 2 years ago.
No ceramic tile except the bathrooms
Customer: replied 2 years ago.
I will be recessing the beam
Expert:  StructuralEng replied 2 years ago.
You’re asking this beam to do a lot of work and it shows in the size, especially if you want to have ceramic tile anywhere. You will need a W21x111 ASTM A992 Gr. 50. The beam is 21.5” deep x 12.3” wide and weighs 111 pounds per linear foot. That includes accounting for a future second floor and attic but having the roof load only the exterior walls.
Customer: replied 2 years ago.
I got a much different size from my local contractor ??? ( 16 x 38 )
I don't know if the fact that he's padding the beam on both sides with LVL makes a difference ?
Expert:  StructuralEng replied 2 years ago.
No. The fact that he is packing the beam with LVL will have almost no impact. The steel is many times stiffer than the wood and therefore attracts the majority of the load, regardless of actual capacity. A W16x40 is overstressed in strength by 50% and will deflect over 3” when fully loaded. The beam is not even close to working for what you want. I don’t know if he considered the second floor and attic or just one floor, but with two floors and an attic and limiting live load deflection to span/600 for the tile, you need the W21x111.
Customer: replied 2 years ago.
Thanks for your input but I'm sorry
I feel you can't give me the proper sizing based on the fact you appear to be oversizing
This local contract does only this type of work and has an engineer on staff and will pull a permit with my township
I would like a refund of your charges !!!!
Expert:  StructuralEng replied 2 years ago.
I’m sorry you feel that way, but I design beams all day/every day for a living. A W16x40 (which is larger than the beam you stated and doesn’t exist) will not span 33’ supporting two floors and an attic with 14’ joists on each side and meet the deflection criteria of span/600 LL deflection for ceramic tile. It’s just not going to happen. It doesn’t even meet that deflection criteria for supporting a single floor, let alone two plus an attic. Do yourself a favor and ask for confirmation that the beam was designed for two floors plus an attic and will meet the span/600 live load deflection requirements for ceramic tile. Otherwise you’ll have more headaches than you want. I wish you the best of luck with your project and will request a refund for you.
Customer: replied 2 years ago.
My mistake the beam he is calling for
w14 x 38
Expert:  StructuralEng replied 2 years ago.
Good luck with your project.

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