How to work out how big a piece of steel should be?

[crazymac]

Hi All, 1st post and i've been scratching my head on this one.

I'm in the process of building a garage and I need to put a piece of steel across from pine end to pine end to support the roof.

My reasons for using a piece of steel is so that I don't have trusses intruding into the roof space as I want the entire height so that I can fit a two post vehicle lift in there.

The total span will be 8 metres, and I have calculated that the weight of the roof tiles (Marley Wessex) will be 3360KG.

I plan on laying two purlings again from pine end to pine end as well as the wall plate of course. and also timbers from the apex down to the wall plate which will be birdmouthed? into the wall plate.

The pitch of the roof will be 23 degrees (to match the existing house roof) and the depth of the garage is 7 metres.

So how big a piece if steel do I need??

 

[freddiemercurystwin]

A big one, something like a 356 UB. Need an SE really, frankly anything else is a bit stupid. Get a calc done online for not much.

 

[crazymac]

A big one, something like a 356 UB. Need an SE really, frankly anything else is a bit stupid. Get a calc done online for not much.

This probably sounds thick but where would I go to get an online calc? I've googled and googled but my search terms can't be right cos i'm getting nothing.

 

[freddiemercurystwin]

Seek and ye shall find

eg http://www.beamsonline.co.uk/ or http://www.beamcalcs.com/index.html

Phoning a few local SE's may also be worthwhile, some may be happy to just do the calcs if you provide all the info they need.

 

[crazymac]

I knew there had to be somewhere, my search terms must have not been very good!

Thank you very much for the links, much appreciated.