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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6686
Experience:  Structural Engineer
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I'm building a patio cover. I need to know the minimum

Customer Question

I'm building a patio cover. I need to know the minimum dimensions for my beams.
I'm using #1 Douglas fir-larch (in southern California).
Local code states:
• Deflection base on L/360 (LL only)
• Load Duration Factor = 1
• Roof live load is 10 pdf
• Roof dead load is 7 psf
• Ceiling joist
Size of ceiling joists will be 4x12 for appearance. Ceiling joist span is 8' o.c.
I need to span 17' from post to post.
Submitted: 4 months ago.
Category: Structural Engineering
Customer: replied 4 months ago.
BTW, I'm looking to use 6x lumber for the beams for appearance.The posts will be 4x6 with a height of 7'-6".
Customer: replied 4 months ago.
Load Duration Factor = 1
Expert:  StructuralEng replied 4 months ago.
Where did you get a 10 psf live load from?
Expert:  StructuralEng replied 4 months ago.
Minimum roof live load is 20 psf
Customer: replied 4 months ago.
You wrote: Where did you get a 10 psf live load from?From the city of San Diego information bulletin for Patio Covers. See attached, page 4, section IX.Thanks.
Expert:  StructuralEng replied 4 months ago.

I see that it says the tables make the assumption of a 10 psf LL and 7 psf DL. I don't agree, necessarily, that 10 psf is the correct live load

Expert:  StructuralEng replied 4 months ago.

The IBC sets a roof live load of 20 psf. Your local code can make it MORE stringent, not LESS stringent.

Expert:  StructuralEng replied 4 months ago.

You can plan for a doug-fir no. 2 pressure treated 4x12

Customer: replied 4 months ago.
Can I replace the Doug-fir no. 2 pressure treated 4x12 beams with Doug-fir no. 1 6x8 beams? This is a patio cover (pergola) so I don't need pressure treated lumber.
Expert:  StructuralEng replied 4 months ago.
Is this exterior?
Expert:  StructuralEng replied 4 months ago.
A 6x8 is not close to a 4x12
Expert:  StructuralEng replied 4 months ago.

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

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