Hi everyone I am seeking flooring advice and hope someone can point me in the right direction please. I moved into a flat last year which currently has laminate flooring in the living room and hallway, I noticed that their are some spongy bits/dips in some parts of the flooring in both areas, they don't creak just bounce if I step on them. I want to replace the flooring with new laminate and want your advice, should I get plywood and underlay then get laminate on top or what would be ideal as ideally I want the flooring not to have spongy bits. Also how thick should laminate be in mm as I don't know whether to go for 8mm or 12mm? Thanks for reading and any information would be appreciated.