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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 7320
Experience:  Structural Engineer
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I am looking to build a patio cover. It will be

Customer Question

I am looking to build a patio cover. It will be approximately 20' deep and 50' wide. I am going to cut into the roof and install posts on the exterior wall to support either an I beam or rectangle tubing. Parallel to the house I will put square or round tube into the ground in steel reinforced concrete on top of which I will put either another I beam or rectangle tube. Then the 20 square tube will span the 20' between the two beams. What are your thoughts?
Submitted: 1 month ago.
Category: Structural Engineering
Expert:  StructuralEng replied 1 month ago.
Hello
Customer: replied 1 month ago.
Hello
Customer: replied 1 month ago.
Let's start with text. If I like what I see we can move to a call.
Expert:  StructuralEng replied 1 month ago.
Do you have any sketches or picture you can share?
Customer: replied 1 month ago.
I just hand drew a small sketch.
Customer: replied 1 month ago.
Do you have any questions on the drawing?
Customer: replied 1 month ago.
No response? I guess that means your not interested?
Expert:  StructuralEng replied 1 month ago.

I could provide a detail on how to join them, but I would need to submit a premium service offer to do that.

Customer: replied 1 month ago.
I know how to join them. My question was recommended size of tubing or I-beams.
Expert:  StructuralEng replied 1 month ago.

As the vertical posts?

Customer: replied 1 month ago.
No
The beams that go on top and the cross beams that connect them.
Expert:  StructuralEng replied 1 month ago.

What is the city and state so I can look at snow loading?

Customer: replied 1 month ago.
Portland Oregon
Expert:  StructuralEng replied 1 month ago.

You can plan for W8x28 beams ASTM A992 Gr. 50

Customer: replied 1 month ago.
What about the 20' steel rafters to span between the beams?
Customer: replied 1 month ago.
Or would aluminum be better?
Customer: replied 1 month ago.
Is anyone home?
Expert:  StructuralEng replied 1 month ago.
I apologize for the delay. It was very late here. What spacing of those purlins do you want?
Customer: replied 1 month ago.
I was thinking 2'-3'. What would you advise for spacing and size?
Expert:  StructuralEng replied 1 month ago.

I would not recommend mixing aluminum and steel unless you provide a dielectric break. Otherwise you will promote galvanic corrosion by having dissimilar metals in contact with each other. There are ways around this, but you would need a very specific detail to isolate the metals from touching each other.

As steel, they could be W4x13 beams

Customer: replied 1 month ago.
That would make this very heavy. I think I should consider assembling the entire structure out of aluminum.
Customer: replied 1 month ago.
I am anxiously awaiting g your reply.
Expert:  StructuralEng replied 1 month ago.

12x7x14.292 for the main beams (6061-T6)

Expert:  StructuralEng replied 1 month ago.

7x4.5x5.8 for the purlins spaced at 3' on center. Both will require bracing against lateral torsional buckling along their length.

Expert:  StructuralEng replied 1 month ago.

Hello. Do you have any other questions for me on this topic? If you could rate my answer, I would appreciate it.