Old building stumps sometimes sink. When old building stumps sink, it creates dips in the flooring level. In this situation, joists loosen from its bearers or stumps and create a bouncing effect. Fixing this problem is usually by jacking up the sections of loose flooring and filling the gaps with new planks.
However, there is not much point in fixing this issue without first determining the root cause of the problem. Knowing the cause will help us decide which materials and tools to use and how to offer the right solution.