Like many 40 years old houses, the one we bought last summer has floors that squeak when you walk on them. Back then, when they but the floor sheathing down, they nailed it and with time as the sheathing cups and warps, it pulls the nails out just a slight amount. Then when you walk across that spot, the wood slides up and down on the shank of the nail making a squeak.
For the most part it didn't bother me for the longest time but when I started trying to sneak around while Baby Abbey was asleep, I found myself avoiding those spots because they would startle her awake. However, some spots were so large that I couldn't sneak past. While this is good for detecting a burglar, it is not so good for letting sleeping babies sleep.
I tried just sinking a wood screw into the squeaky spots but it was a very time consuming affair. I had to first probe to find the floor joist and once found, sink a screw in the same spot. Then I had to repeat the entire process 16 inches along on the next joist. So I did some internet searching and found a pretty nifty kit for fixing floor squeaks under carpet. It worked so well, I thought I would pass on the word.
Squeeeeek No More as it is called can be found on Amazon and comes in a kit. The first part seen above is the probe to easily find a floor joist. I would take a hammer and hit the floor to get the approximate position of a floor joist and use the probe in my drill to get a precise position. You can tell when you drill into a joist by reversing the drill. If the probe comes back out, you're in a joist. If it just sits and spin, you are in a cavity. Before this I used a nail and sometimes that was hard to tell if you were in a joist or not.
The next item in the kit was this three legged spacer. You used a special bit shown later to screw down into the joist. The offset allowed the screw head to remain sticking above the carpet for reasons discussed below.
Above is the special screws that came with the kit. They have two different thread pitches which pull the plywood sheathing down to the joist as you are screwing into the wood. Also, above the last thread, the screw is necked down to allow you to break off the head of the screw. The spacer above is the proper height so that the screw breaks off just below the surface of the sheathing so you don't get anything poking you in the soles of your feet.
Finally, above is the special bit with the square drive on the end that is spaced to get everything just right.
This picture shows you the portion of the screw remaining above the carpet before being broke off. In the picture of the spacer above, there was one arm that had a recess that was supposed to slip over the head of the screw to give you leverage to break it off. While it did work, I only did it a couple of times because I could tell if I did it too many times, I would end up breaking the plastic spacer. This was the only fault I had with the entire system. But a whack with a hammer sideways on the screw head was all I needed to break off the screws and it was probably faster that way anyway.
Finally, I ended up locating the joists on each side of the squeaking area I was trying to silence and leaving the screw heads sticking up. I then used string to show me the joist locations so I could run down the line sinking a screw every eight inches or so. Once the area was complete, I knocked the heads of the screws off and rolled up the string. It worked great. Now my floors feel and sound solid once again. The kit came with two of the joist probes and only one of the square drivers. If I were doing a lot area, I would probably order another driver because the nature of the process rounds it off gradually until it is useless. Also note that there is a different attachment included for fixing squeaky hardwood floors which I didn't use.
Long term, we plan to install hardwood throughout the entire upstairs and before doing that, I plan to properly screw down all the sheathing once the carpet and furniture is removed from the rooms. But before we do the hardwood, we may complete an addition to the house in the next couple years and I didn't want to rip up the carpet until we were ready to do it all in one shot. So this was a temporary fix to preserve our sanity while we plan and complete the addition.