Flooring on upstairs making noise while walking

[chukwe]

Just moved into a beautiful house 6 weeks ago and the upstairs floor is making cricking noise while walking.

How do we fix it?

Pull back the carpet and see if there are loose floorboards. If they're loose, you might be able to hammer them in. If they're damaged or broken, they'll need to be replaced.
It's fairly straightforward. The hardest part is accessing the place if there is carpet.

I expect the floor is shoddily-fixed chipboard. Sorry.

It is probably nailed down so difficultto lift or tighten. The tongues and grooves may be glued together. Look for the lines of nails, there is probably a joist under each. Are there any joints that are not over a joist? These are the ones most likely to squeak. If there are any cracked sections, they ought to be cut out and replaced.

If you put any additional screws in, there is a risk you may go through a pipe or cable. When you lay your own floor, paint or pencil on all such runs so you can avoid them.

if you ever take it up and replace it, I recommend ply, screwed down (so you can tighten or lift it non-destructively) and with struts (like noggins) under ALL unsupported joints.

opinions differ, but chipboard has the advantage, to builders, of being very cheap. I don't know of any advantages to the homeowner.