Depends entirely on the floor. As Rosebery says, anyone posting a yes or no here is just guessing but please bear in mind this is almost 30 stone plus your weight and both of these are just dead loads. You jumping up and down is a considerable addition to this.
400lb downloading over a smallarea plus your weight...seems a lot to me, but what do I know..only been building for thirty five years.. :wink: .I would have thought you would need to at least double up on the joists, but then again depends on the size and spacing of existing joists, span of room etc. Obviously the thicker the joist and the smaller the span, the better the loading capability. In older properties with smaller joists, I,ve had to reinforce the floors just to take the weight of a bath... If you could give us a clue as to the layout and subfloor I might be able to advise further,but as previous posts have pointed out you would benefit from a full survey
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