All hardwood floors expand and contract with changes in the temperature and humidity. Older floors were mostly constructed of tongue-and-groove strips of varying widths and lengths on top of a sub-floor. The two layers were separated by a layer of felt or resin paper to eliminate noise from the layers rubbing together. But over time nails will come loose as a result of repeated expanding and contracting and cause the floor to float above the sub floor. When you walk over the area the floor sinks back down and the nail is pushed back into it’s hole and causes the squeak.

To stop the squeak you must re-anchor the flooring. There are several methods you could use, each with it’s own unique procedures. If the squeak is on a ground level floor and you have access to the sub-floor from the basement then ordinary drywall screws can be used. Locate the area that is loose and make sure you can get to it. Pre drill holes for the screws using a combination counter/sink drill bit that is the correct size for the job. If the sub-floor is 3/4” thick, and the flooring is 3/4” thick your total thickness is 1 1/2” so you will want a screw and bit no longer than 1 1/4”. This gives you a 1/4” cushion so you do not poke through the hard wood floor. The size of the holes are very important. The counter sink/bit should make the hole through the sub-floor just big enough for the screw to pass through but not grab. The hole in the underside of the flooring needs to be small enough for the screw to grab firmly but not so small as to cause the flooring to split. It is also necessary to have someone (or something) stand on the floating area to press it when drilling or inserting the screws. Tighten the screws only enough to seat them. Do not over tighten or the screw will sink into the sub-floor and may poke out the top of the hardwood floor. Also, remember a screw is a wedge that goes around in a circle and can make things split. Old hardwoods split very easily. Always pre-drill the holes.

If you cannot get at the sub-floor your only choice is a surface attack. This is generally done using a finish nail, nail set and a hammer. If the board to be nailed is cracked or split you may want to replace it. Adding nails to a split board is merely a short term quick fix that will need additional attention in the near future. If the board is in good shape one or two nails in it and the adjacent boards should take care of the noise. Nails should never be placed closer than 3/4” from either side ( the tongue and groove area will split ) nor within 4” of a butt joint or end of the board. If you have a butt joint in the floating area, secure the boards on both sides of it to resolve the problem. Pre-drill holes through the flooring only at a 45 degree angle in the direction of the grain. You can use an 8d finish nail with the head snipped off as a drill bit to get a perfect fit. Stand on the board with the hole just at the tip of your foot to place all your weight on it and tap the nail in until it seats firmly. Then use the nail set to push the nail just below the surface. After you have seated all the nails required, wet each nail hole with a drop or two of warm water. This will cause the wood to first soften, then expand and engulf the nail head making them much less noticeable. When dry, a little wax or other floor polish should conceal them even more.