what size rsj to use to cover 25foot span

valtra2

hi putting up a shed myself and just wonderind what size rsj to use to cover 25 foot span

blue5000

I've done 27 ft with 100mm X 200mm(8x4in), hasn't fallen down yet, but I did weld a few tri-angles at the top of the pillars so that there are 6 bolts each end instead of the usual 2.

Does anybody know of any engineering web sites that have this sort of info?

pakalasa

It's not as simple as spec'ing a size to cover a certain distance. RSJ's are very strong when they are loaded directly across the wider section, but are not strong when twisted or loaded across the narrow width (from the side). You have to consider therefore the overall structure and what loads the roof is expected to stand up to.

It might seem fine, but will it stand up to strong winds or a storm.

Shauny2010

That's like asking what length is a piece of string
is the rsj been used to carry a load ? or just its own weight/ Will the joist carrying a floor ?

tismesoitis

agree with blue there 200*100 is prob the best value to go with. just b careful that u have a decent enough pitch anywhere around or above 15 degrees any lower pitch and a good fall of snow might just test it:o. if u think u need stronger then weld a 50 or 75*10 length of flat on its edge the full length of the beam and jobs a great one:)

JohnBoy

I'm all about the DIY myself, but getting beams sized is a job for the professionals.

at the very least find an identical build and measure the beams used, but really so much depends on the particular application.

you could be totally undersizing, or for that matter spending way too much on a DIY sized beam.

pakalasa

Valtra2,

Info on RSJ sizes and spans on page 7 of the following;
http://www.agriculture.gov.ie/media/migration/farmingschemesandpayments/farmbuildings/farmbuildings/wordandpdfdownloads/S101.pdf

DAFF website

blue5000

also here on corus steel site

http://www.corusconstruction.com/en/about_us/panels_profiles/technical_support/load_span/