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Discussion Starter · #1 ·
In Phoenix, Arizona I have a flat roof over an outdoor space at the back of my single story house. The roof in question does not have a load above it and does not experience any other notable load due to weather, etc.

It's a triangle in shape with sides of 14', 14' and 20'. Essentially, it is a 14' x 14' square cut in half diagonally with total coverage of 100sf. The roof extends from both14' sides constructed of cement block exterior walls and has the 20' span supported on both ends at the walls with a post in the middle (approximately).

I want to remove the center post on the 20' span. Can I do this with a 6" x 6" x 20' piece of lumber for a beam and notching into cement block walls for support? Or do I need and engineered wood beam like a glulam? My preference, besides price, is to avoid losing clearance with a taller beam. If 6" x 6" is not sufficient, are there recommendations for an engineered product that isn't too tall?

I will try to attach a few pictures. Thanks.
 

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If you don't want an LVL beam because of height issues, you would need a steel beam instead (calculated and specified by a SE). A 6"x 6" timber beam would deflect too much on that span.
 

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This is a relatively simple beam design problem, so no doubt you are trying to avoid paying a structural engineer to size a beam. You might get someone on this forum to size it for you, but the licensed folks on here would not do that, since it would be unethical and probably illegal for a licensed professional to offer structural engineering advice on a job they have not seen. So at best you will get an unlicensed person to offer advice, which may be correct, or may be wrong, but how would you know?

My suggestion is to discuss this project with your local building inspector, who may be willing to tell you what size beam you need in lvl, steel, or sawn lumber. The size will be based on the roof loads. I know you don't get snow down there, but wind loading on a flat roof can be surprisingly large, and could control the design. Alternatively, you could go to a local lumber yard (not a big box store, a real lumberyard), and they may be able to size a glulam beam for you as part of the cost of buying the beam. Some lumberyards have a structural engineer working for them part time for just this purpose.
 

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This is a relatively simple beam design problem, so no doubt you are trying to avoid paying a structural engineer to size a beam. You might get someone on this forum to size it for you, but the licensed folks on here would not do that, since it would be unethical and probably illegal for a licensed professional to offer structural engineering advice on a job they have not seen. So at best you will get an unlicensed person to offer advice, which may be correct, or may be wrong, but how would you know?

My suggestion is to discuss this project with your local building inspector, who may be willing to tell you what size beam you need in lvl, steel, or sawn lumber. The size will be based on the roof loads. I know you don't get snow down there, but wind loading on a flat roof can be surprisingly large, and could control the design. Alternatively, you could go to a local lumber yard (not a big box store, a real lumberyard), and they may be able to size a glulam beam for you as part of the cost of buying the beam. Some lumberyards have a structural engineer working for them part time for just this purpose.
What he said!
 

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Discussion Starter · #5 ·
Got it

Thanks for the replies. They make a lot of sense. I will research locally.

@Daniel Holzman - go B&B !! That's Belichick and Brady.
 

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whatever beam you decide it will need to set in deep enough to rest on the wall framing( stud pocket both sides) and not the brick facade.
 
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