Best way to strengthen upstairs floor

weeg

jblakes said:

4m, it was placed where the wall was.

Surely you don't need a structural engineer or BC to strengthen the floor, it's perfectly fine just abit bouncy. I'd like to stop as much bounce as possible. 

If you want expert advice, ask an expert. Believe me when I say that no-one on the internet can properly answer your question without seeing your house, and that builders don't always know what they are talking about.

If you start putting steel beams into your house without consulting someone who knows what they are talking about then that risk is totally on you. Especially if you don't want a downstand.