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StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 7185
Experience:  Structural Engineer
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I'm trying to find out what wood I should use to build a green

Customer Question

I'm trying to find out what wood I should use to build a green roof with a heavy load
JA: OK. Tell me a bit more about what's going on so we can help you best.
Customer: "Hello, I am trying to build a shed with a green roof. Obviously the green roof adds a lot more to the load of the roof. The span I'll have is 3 meters and the dead load of the roof is 150kg per square meter. The shed will be 3 meters x 4meteres with a 600m overhang on the roof on all sides.
JA: Is there anything else the Structural Engineer should be aware of?
Customer: I was going to build the stud walls out of 4x2 so I want to know what the spacing will be required for them. Also I want to put in double doors with a span of 1600mm so I would like to know what I have to for the structural part of the frame around them. There will be 2 windows too but I haven't acquired them yet so I'm not too sure how wide they will be but I would imagine around 700mm each.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Structural Engineer about your situation and then connect you two.
Submitted: 1 year ago.
Category: Structural Engineering
Expert:  StructuralEng replied 1 year ago.
Expert:  StructuralEng replied 1 year ago.
That's relatively light for a green roof.
Expert:  StructuralEng replied 1 year ago.
It sounds like you need the entire shed engineered. Is that correct?
Customer: replied 1 year ago.
I'm more concerned about the beams I need to put in to support the load of the roof as they will have a span of 3m. I'm fairly confident about the walls as they will have 2x4s every 455mm. I'm told that one 2x4 has a load limit of around one tonne compression so I'm sure the walls can take the load (but any further information greatfully recieved)
As for the doors and windows I'm a bit uncertain what to do there load wise as obviously I wont be running the 2x4 through those spaces.
So what do you think? Anything else I need to worry about or is it just selecting the correct gauge timber for the roof?
Expert:  StructuralEng replied 1 year ago.
Do you mean joists?
Customer: replied 1 year ago.
Joists or rafters. Its going to be a flat roof, I forgot to mention that which is silly of me.So stud walls made out of 4x2 holding up a green roof with a load of around 150 to 200kg per square meter.What size rafters (or joists) will I need to be able to span 3meters. And how far will they need to be spaced apart?Thanks,Damian.
Expert:  StructuralEng replied 1 year ago.
Use 2x10 @ 16" o.c.
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.

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