Garden room.

[VictorianModern]

Test

 

[Notch7]

it sounds like the floor joists arent fully supported either because the foundation has moved or because it wasnt set out level.

Im sorry Im not quite unerstanding your description of what has been done

 

[domdee]

maybe the floor timbers aren't big enough. how long are they and what size are they? and how much spacing is there between them?

I'd have though they'd be something along the lines of:
2m long. 150x50mm. spaced every 400mm