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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6682
Experience:  Structural Engineer
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I need to span a 20 foot section with only support on each

Customer Question

I need to span a 20 foot section with only support on each end, no center post support. this is for a patio. the patio will be made out of normal roof material for a flat roof 20' x 20' 2x4s 3/4" plywood and roof top stuff. fairly light weight. we get very little snow in Tacoma WA but with that being said you never know we could get an od snow storm in the future perhaps 13" or 15" (unlikely) but you never know. the structure is tied to the house on two sides and a large beam on the far end. 10X6 wood beam with 4 support post. I will not remove this what size steel I -beam size should I get for this?
Submitted: 4 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 4 months ago.
Hello
Expert:  StructuralEng replied 4 months ago.
I can help
Expert:  StructuralEng replied 4 months ago.
2x4 rafters?
Expert:  StructuralEng replied 4 months ago.
Is this a fable roof or a shed roof?
Customer: replied 4 months ago.
shed roof
Customer: replied 4 months ago.
2x4 rafters? yes
Customer: replied 4 months ago.
what size steel I -beam should I get for this?
Customer: replied 4 months ago.
House o
I----------->o<-----------o
house I > < o this is the best I can draw for you 20' X 20' patio
I----------->o<-----------o
Customer: replied 4 months ago.
drawing did not send as intended
Expert:  StructuralEng replied 4 months ago.
2x4 rafters spanning 20' is too far
Expert:  StructuralEng replied 4 months ago.
I will size the beam, I just wanted to point that out
Customer: replied 4 months ago.
The 2x4s are not spanning the 20 feet, they are resting on the two support beams in place at this time. Tied to the house at one end resting on the center support beam then resting on the outside support beam on the other end, three resting points. This is sound. My question is about the center beam. I want to take out the center support post that in the middle of the patio floor. I have to work around this with all my activities and placement of patio stuff. I want this “post” gone I need to know what size steel I-beam to install that will be strong enough to support a patio flat shed type roof. Probably well under 3000 lbs. it may snow sometime in the future. I walk on this to sweep and blow leaves off from time to time. No other activities on this roof other than that. I will be installing this I-beam manually with a friends help. So I don’t need an overkill that will be too heavy to handle. However I want enough support.
Customer: replied 4 months ago.
I would like to get started on this project this weekend. any chance I could get this answer today?
Customer: replied 4 months ago.
am I clear on my question, or do you need more information from me?
Expert:  StructuralEng replied 4 months ago.

I apologize for the delay.

Expert:  StructuralEng replied 4 months ago.

I have everything I need.

Expert:  StructuralEng replied 4 months ago.

You can plan for a W8x28 beam ASTM A992 Gr. 50 beam. It's a steel I beam, 8" deep and weighs 28 pounds per foot.

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