I don't know about the rest of the country, but it's becoming quite common to build your roofs/floors like this (except tilted roofs ofc); there are so many systems :p . We used the same principle for our new bathroom and kitchenette floor. The old wooden beams and wooden flooring were ripped out and replaced with this. It's much stronger, doesn't rot and is no fire hazard.
See:
As for the raised beds...It's not only a budget issue, but also...Well, the walls still need to be treated and finished, otherwise any paint, tiles or brickwork against them will come off eventually due to moisture seeping through. And doing all that is hard when there are plants in front. They'll get trampled or painted themselves eventually :p
I could always lift them during dormancy, but then I'd have to find another spot to place them and that's space we don't have atm
