GloriainX

On the 16' span I told them to put 3 lines of bridging's, I'm guessing that will be enough? Some years of my life were spend in roofing so although I've got a general feel for what will be sufficient, I'm still no engineer, so its nice to have confirmation.

Thanks Peter. I'm in Ireland and grew up using imperial so nowadays i used a combination of both, eh imperietric? So they ended up going with I believe 220mm x 44mm at 300mm centres so that should about bring us up to 40psf im guessing? Do you mean by sister and bolt, to double up every fourth joist while maintaining 300mm centres? Would that be perhaps overkill if they are using 220's at 300 centres? Cheers for your input.

Thanks Peter for all that information, much appreciate it! So if we use 47x220's (its C16 min unfortunately, no C24 avail) at 300mm centers over a 15'3" (not 16', sorry) span that will be more than enough would you say without the need for any supporting beams, for a live load of 40psf? It would not cost much more than the 175mm (there are no 195's available here or I-joists, we were gonna make our own for the beams..) so considering how much extra the supporting beams woulda cost it would probably work out cheaper using the 220's without a big beam encroaching down from the already pretty low ceiling (7ft). If that kind of structure will take 40psf live load then we are singin. (can't find a span calculator that will use 9", just 8" or 10" so if anyone can weigh in to confirm the 220's (9") will achieve 40psf live load at that span please feel free to chime in.

Hi everyone, I'm helping a friend build a structure in his shed which is 16' x 16'. He also wants a second story on it but he is doing it on a budget so we were thinking 7" x 2" joists at 12" centres for the ceiling/floor joists. I was just wondering what size of a beam we would need running down the middle to support it all? i was thinking of 12" osb i-beam with 3 laminates. Would two of these, side by side in the middle, stretching along a 16' span, be enough to support that second floor without the need for a pillar in the middle, or would a pillar be required? There may be upwards of ten people up there and we want to make sure everything is as safe as possible. I was going to put a pillar in the middle to be sure but if two 3 ply 12" osb i-beams would be enough on their own then freeing up that space would be great. I could figure it out if it was a steel or aluminum ibeam but im stumped when it comes to osb. Thanks!