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Category: Structural Engineering
Satisfied Customers: 7264
Experience:  Structural Engineer
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# How thick and tall does a laminated beam need to be to

### Customer Question

how thick and tall does a laminated beam need to be to support a second stroy ceiling that spans 17 feet?
Submitted: 1 year ago.
Category: Structural Engineering
Expert:  StructuralEng replied 1 year ago.
Hello
Expert:  StructuralEng replied 1 year ago.
I can help.
Expert:  StructuralEng replied 1 year ago.
Is it supporting an attic only?
Is the beam span 17'?
What is the joist length on each side of the beam?
Customer: replied 1 year ago.
17' square room
Attic above
Beam will go 5 feet in from rear
Supportin 2x8' ceiling joists that meet at this beam point
One roof spar connects 6 feet in from side
I need dimensions for laminated beam to support the 17foot span
Estimate is 6" wide X 12" tall X 17' span
Expert:  StructuralEng replied 1 year ago.

So this is supporting attic from both sides and roof from one side?

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

What is the attic joist length on each side? It sounds like 12' on one side and 5' on the other.

What is the rafter length on the side supporting the roof?

Customer: replied 1 year ago.
Sugar Land, TX
Yes on 12 and 5
Yes on one roof rafter spar tying on to this span
The attic support is only on outside walls ( room is in corner
Inside wall is non supporting
Expert:  StructuralEng replied 1 year ago.

Supporting the attic and roof, you can plan for a 5.25" x 14" 1.8E LVL to limit deflection to L/360.

Customer: replied 1 year ago.
I want to be sure I understand your numbers
1.8E LVL to limit L/360 means...
Expert:  StructuralEng replied 1 year ago.
1.8E is the stress grade of the LVL
Expert:  StructuralEng replied 1 year ago.
L/360 is a common deflection ratio
Expert:  StructuralEng replied 1 year ago.
That means the deflection 1/360 of the span
Expert:  StructuralEng replied 1 year ago.

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