The engineer mentioned sister joists to reduce bounce, but there's a lot of structure in the way that would make full length sister joists very difficult to install.
Would some joist stiffeners be a suitable workaround? Either bridges, or metal straps, or something along those lines? I have no idea how effective that would be, if at all.
I'm not disagreeing with either of you guys, you obviously know your stuff as I do.
But the above highlighted point is the issue I am referring to.
If there is no way to get joist in @ 300 centres or to double up the joist and get adequate bearing on the plates then it is impossible to get it to meet the span tables or code.
Therefore, whatever means are used to stiffen the floor (I'm sure we all agree it can be done) would need to be be deemed to meet the performance requirements of the BCA.
I think part of the issue is over here in the West we are only just moving to having private certification (as of last year). Typically all plans had engineering details provided by an engineer. These plans were approved by the relevant council and you couldn't change them without going back to the Engineer.
Most building is still done this way.
If I was the builder in this situation I would need to go back to the Engineer and let them know the issue and what I was going to do to meet the performance requirements. If I could simply make some changes according to span tables or the code then I wouldn't bother talking to the Engineer but if that wasn't possible (as seems to be the situation here) then I would need to run the options pass them and get their approval. I guess as private certifiers become more common they may end up being the ones you speak to however I'd probably still choose to talk to the relevant Engineer.
Bottom line is, you follow the approved plans.