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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6681
Experience:  Structural Engineer
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I am building a free standing gazebo with a colorbond roof.

Customer Question

Hi I am building a free standing gazebo with a colorbond roof. It has a span of 4.5m.
JA: OK. Tell me a bit more about what's going on so we can help you best.
Customer: What size lvl beam or F7 treated pine beam would be required?
JA: Is there anything else the Structural Engineer should be aware of?
Customer: The ceiling will be lined.
Submitted: 2 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 2 months ago.
Hello
Expert:  StructuralEng replied 2 months ago.
I can help
Expert:  StructuralEng replied 2 months ago.
What is the length, on each side of the 4.5 m beam, of the framing supported by this beam?
Customer: replied 2 months ago.
It will be a truss roof held up by 4 posts. 4.5m wide X 3m deep
Expert:  StructuralEng replied 2 months ago.
The trusses are 3 m and the beam will span 4.5 m?
Customer: replied 2 months ago.
what size lvl beam would be required
Customer: replied 2 months ago.
trusses will be 4.5m wide
Expert:  StructuralEng replied 2 months ago.
the beam will only span the then, not the 4.5m?
Customer: replied 2 months ago.
The beam will span from post to post 4.5m anf the trusses will sit on them
Expert:  StructuralEng replied 2 months ago.
Something doesn't make sense. Earlier you said its 4.5 m X 3 m, but you say both the beam and truss span 4.5 m
Expert:  StructuralEng replied 2 months ago.
Which is correct?
Customer: replied 2 months ago.
Sorry the truss span is 3m
Customer: replied 2 months ago.
Please see attached
Expert:  StructuralEng replied 2 months ago.
You can plan for a 150x300 F7 timber treated pine
Customer: replied 2 months ago.
What about an LVL beam.
Expert:  StructuralEng replied 2 months ago.
LVL are not intended for exterior use since they can't be treated
Customer: replied 2 months ago.
I don't understand the size of the F7 beam 150mm X 300mm I haven't seen that size.
Customer: replied 2 months ago.
The LVL beam would be have cladding over the top.
Expert:  StructuralEng replied 2 months ago.
Those are the nominal dimensions. The actual dimensions will be slightly smaller
Expert:  StructuralEng replied 2 months ago.
But it's still subject to moisture from condensation and driving rain. It's not recommended for use other than in a dry environment
Customer: replied 2 months ago.
The alfresco attached to our house was constructed using LVL beams.
Expert:  StructuralEng replied 2 months ago.
Read the last line of the very first paragraph on this page
Expert:  StructuralEng replied 2 months ago.
http://www.pinetimberproducts.com.au/products/lvl/
Expert:  StructuralEng replied 2 months ago.
A builder may have done it, but that doesn't make it correct. LVL are not intended for outdoor use
Customer: replied 2 months ago.
OK. The biggest F7 beam is 240mm X 45mm. Would this be ok
Customer: replied 2 months ago.
Sorry its 290mm X 45mm
Expert:  StructuralEng replied 2 months ago.
I see 45x290. You will need four of them
Customer: replied 2 months ago.
4 laminated together
Expert:  StructuralEng replied 2 months ago.
You need four of them
Customer: replied 2 months ago.
4 on one elevation
Expert:  StructuralEng replied 2 months ago.
Correct
Customer: replied 2 months ago.
Hoe is this done. No chance it has 4 beams one side
Expert:  StructuralEng replied 2 months ago.
Four side by side
Customer: replied 2 months ago.
The pic clearly shows there is not 4 side by side
Expert:  StructuralEng replied 2 months ago.
You take four 45x290 and nail them together. This is done all the time. A single 45x290 is a joist, not a beam
Expert:  StructuralEng replied 2 months ago.
I'm not basing my analysis on a picture.
Expert:  StructuralEng replied 2 months ago.
The analysis is based on numbers. This is not even the same setup you described. You described a rectangular plan with trusses. This is a square plan with a stick framed roof
Expert:  StructuralEng replied 2 months ago.
They are completely different

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