Roof joists

[racket]

Hi,

Can someone tell me, if I have a garage 7m X 7m and i want to put a flat roof on top will i have to use steel beams as you can't get wooden joist's 7m long. Should I run 2 steel beams across the roof and span them with 4X2 and then stirling board on top. Can someone point me in the right direction. what size I beams will I need so the roof won't sag
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[noseall]

perhaps fit a 205mm x 105mm rsj at centre span, wall to wall, bolt a 100mm x 50mm timber on top using m12's, then 150mm x50mm joists should suffice. building controll or a structural engineer are the best to advise or confirm.

 

[racket]

Cheers for that noseall, you have given me a great idea, maybe raise the rsj off the wall at each end and create more of an apex roof rather than a flat roof this would be better for water run off.
in your opinion do you think this rsj would do the job, don't really want to get structual engineers involved how much do they charge
Is there any websites you know off that could help me out

cheers again

 

[noseall]

pitched roofes (apex) steal light from your neighbours and require planning permission, a whole new animal. tread carefully my friend!

 

[Static]

7m span is quite large, youll be looking at a single 203x203UC section running mid span probably with 170x47 C16 joists for the flat roof.
Laying the structure flat then using firrings to create a 1:80 fall is the simplest way. A structural engineer will probably charge about £100 for a single beam design, costs you nothing to get a quote.