Squeaky Chipboard Subflooring

In my opinion the floor needs lifting and re laying with ither silicone or expanding glue on the joists and in the joints

Agree with JWB on this; Best scenario is lift the floor, apply a generous bead of clear silicone to each joist, leave overnight to cure, re-lay board with self-countersinking screws every 300mm. If this is not practical or possible, skip the first part and simply screw every 300mm. In answer to which trade, a carpenter.

Just screw the existing chipboard to the joists every 300-400mm. You'll probably find the chipboard was only nailed which is why you're getting squeaking.

A couple of points: When screwing flooring down there are specific flooring screws required. You can’t just use “any average screw”. Flooring screws have threads designed for that purpose and are required by build regs. First I would try replacing existing screws in “like for like” holes. If adding any new screws (should be every 300mm on joists), you need to know for certain that no joists are notched for cable or pipes. Chip board for flooring has to P5 or SP101 (building regs rated). Is it? Squeaking (with traditional floor boards) is often a result of floor boards rubbing against nails / loose nails. It’s no different with chipboard. With so many cowboy new build contractors (just YouTube search “new build snagging inspector”) for all the unbelievable cowboy new build tricks, it could well be that they took the easy route on this job and nail gunned the floorimg to the joists! If so, remove and replace with designated flooring screws. Failing all the above lift and adhere down then screw.