Sounds like they might be nailed down and over time they have moved/lifted slightly! could be down to people walking on this area and heating maybe making the boards retract and expand.
Best remedy if they are all sound is to screw them down.
Lift the creaky boards first and de-nail then check for pipes and wiring as if you go at it without checking you may screw through something you shouldn`t :(
Once lifted and cleaned up then screw down with maybe 40/50mm screws.

Scott.

Screw them back down but make sure you don't hit any pip or cables under the floor boards
You can try talcum powder in the joint
Good luck

Regards
Billy

The noise usualy comes from the board rubing up and down on the nail it is fixed down with, sometimes two boards rubing together. The best way to stop it is to screw the board down, BUT CHECK FOR PIPES AND CABLES FIRST. Most noisey boards hve previously been lifted for electrical or plumbing work. hope this helps.

Hi,

They have either been loose fitted/ nailed down when removed for access i.e plumber/electrician.

if nailed they can creak as the board moves on the nails.

If the carpets are removed then just check which are loose and refix with screws instead.( but check underneath to make sure not to screw into pipes or cables)

Hi Alice
If the boards have been up for tradesmen to lay pipes or wiring then lift them to check what is underneath mark the top of each board with a pencil or similar to show pipe positions or cable runs before you screw them down.
if they have not been lifted then screw a 1and1/2" no 8 screw (38mmm long) screws into the board right next to each existing nail if the nail never hit a pipe then the screw wont either and it will tighten up each nail in the process this also works on chipboard floors you do need to hit the joist each time if you miss you should know so take the screw back out and try the other side of the nail
Be prepared to add or tighten the screws again in a year or two as they will in some areas start to squeak again but you will be able to see the pencil/ markings where the pipes and cables are so it will be much easier you should use a battery drill to fit the screws in with.
I hope you all find this helpful if so click the like button
Kelvin