Once the sparky (electrician) left we looked at the levels in the floor. In the past there was a renovation an add on, and the builder at the time didn’t get the floor levels right so there was a bow in the floor and over time the nails lost their grip and hence the squeaks and other.

I decided that the easiest and cheapest fix was to pack the top of the joist and then lay the structural ply over the packing and existing sheeting. This was then liquid nailed and the ply was also battern screwed in some sections. The existing skirting was reused and the levels looked right and the floor sounded right. Which was no squeaks.