Mains, PSUs and other goodies.

[Rogue]

Another, better, option is to add a second joist on top of the first a 4 x 2 on top of a 4 x 2 will make a huge improvement, however it does mean that you'll have a step up into the room, headroom is reduced and inward opening doors have a bit of an issue - but this is whats often done for loft conversions.

...surely if you can spread the load by placing the benches on their own 'joists' running perpendicular to the existing joists the area...

They say that great minds think alike, but then again they also say that fools seldom differ. This is the first thing that occured to me when I read the post. Can the joist be on top of the floorboards? Basically creating a raised platform at one end of the room? Hopefully Jonathan and I have great minds but I must admit I'm not doing our side any justice at the moment.

Edited to add: Ahh, I guess you mean the extra joist being lined up exactly on top of the old joist, not perpendicular to it? Still, same question applies!