A squeak in hardwood flooring is caused by two pieces of wood rubbing against one another. One way to stop the sound is by reducing the friction of the moving pieces using a lubricant. I’m not talking oil here, but rather a dusting with ultra-fine graphite powder.
This is available at your local hardware stores, and for the most part it’s used to free lock mechanisms. But if you pour a tiny bit of it on the floor so that it can work its way into the squeaking boards, it could very well reduce or eliminate the sound.
If that fails, you can always try a pair of well-placed nails. You first need to pre-drill some slender holes into the wood, angled slightly towards one another. Then drive the nails in, being careful not to bang up the hardwood floor with the head of the hammer.
You can use an 8d or 8-penny finish nail, which has a very small head. Then sink it below the surface of the wood using a nail set. Now you can say good-bye to that squeak forever. You would need a hammer, a small drill bit, and a cordless drill. This would take no more than 15-20 minutes to complete.
Now after you get rid of all the squeaks, use a filler stick in the same color as the floor to fill any nail hole that are visible. When your floor is really starting to show its age, you’ll be able to renew its surface for about a quarter of what it would cost to install a new floor.
You can sand and refinish them, usually up to a total of four times before so much wood is ground away that the nails holding it in place begin to appear. Your hardwood floor should be as good as new.