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Patrick, Construction Project Manager
Category: Home Improvement
Satisfied Customers: 2429
Experience:  30 years commercial construction and 23 years house remodeling projects
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I need to know what size I-beam to span a 35ft. distance with

Resolved Question:

I need to know what size I-beam to span a 35ft. distance with a load in the center of the beam of 3000#. This is not figuring the weight of the beam, just the load on it. I would prefer to use a 10 or 12 inch deep beam. I need to know the weight and width to use.
Submitted: 7 years ago.
Category: Home Improvement
Expert:  Patrick replied 7 years ago.
So you have a point load of 3000 pounds? This is not a distributed load?
Customer: replied 7 years ago.

I assume a distributed load is the total load across the floor of the loft which is about 10,000 #s. I calculated the weight which would be at the center of the beam (3,000#) because I thought this would be the weakest point of the beam. I also don't know if you need to figure the weight of the beam in these calculations? Thank You

Expert:  Patrick replied 7 years ago.
I am concerned about what you are carrying on this beam. What are you supporting it on at the ends and what is the foundation that your are transferring this load down to?
Customer: replied 7 years ago.
The beam will be resting on 3- 2 by 6's nailed together. The floor is concrete 12 in. deep by 3 ft. dia. where post goes at each end and 6 in. deep for the remainder of the floor. The loft is 8 ft. wide and 35 ft. long. The side opposite the beam is nailed to a wall on 2- 2 by 12's and has posts of 2- 2 by 6's every 7.5 ft. for support. Joists are 2 by 8's on 1 ft. centers 8 ft. long weighing 756# XXXXX floor is 2 sheets of 3 quarter in. plywood weighing around 1728 lbs. The other side will be the 35 ft. beam, so half the 10,000 lbs. will be on the beam with approx. 3000 lbs. at the center. The weight will consist of shop parts, empty pallets, a few bags of seed, mostly storage. Thanks.
Expert:  Patrick replied 7 years ago.
Did some checking and for what you have proposed you are looking at a 14" to 16" steel beam. I need to look at the weights per foot for this. You really need to get a structural engineer involved in this. Putting a 35' steel beam on 3 each 2x6s for support on each end does not sound right. You really need some steel columns and engineered base plates to handle what you are proposing. You have your load for framing and then what you intend to load on it for storage. You need to have a safety factor designed in. Improperly done this could be a disaster.
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Customer: replied 7 years ago.
I believe you are correct about the 3 each 2x6s for end posts. This was the contractors idea. I was trying to save around 1000-1200 dollars by not using a structural engineer. That would pay for that steal beam. Thank you.