Advice needed on build over wooden joists

Hello Fellas, I'm about to start the building of another studio! (yes. its not mine but it belongs to my business partner and its going to be built in the same place that I did mine, so I'm pretty involved) The thing is I'm not sure how to proceed about this build, because the room thats going to be designed to "live room", its made of wood joists. And I'm not sure if that will support all the weight from the new "room in a room" construiction on top. To make it more clear for you, the wooden joists are not touching the ground itself, they are "free standing" about 50-60cms from the ground, and supported by "kind of studs"... can you picture that? In other words, the floor joists are not touching the ground that could provide an extra support for anything that could be put on top...however, they are freestanding over some vertical studs from the ground . So.. We have two options: - Remove all the existing old laminated floor thats nailed to the floor joists, and also, remove the joists as well in order to make a new concrete slab directly from the ground. That obviously is the best option, since we will gain about 60 cm of height, and it will provide a solid foundation to build the new inside leaf. - Build the new inside room on top of the joists. But I'm not sure if these will support all that weight. Any help??? Maybe some of you had this kind of problem before, and option number two worked just fine (because, budget, as always in an issue here) Chers

A picture showing the floor joists

I think you need an professional (construction) engineer to have a look and advise you.