How to Silence a Squeaky Floor
Some people think that a few squeaks in a floor give a home character, to others squeaks are a major pain in the neck. If you agree with the folks who think floors just shouldn't make any noises, you may be in luck. As long as you have access to the underside of that squeaky floor, you can probably fix your squeak. Unfortunately however, if you have finished ceilings below your squeaky floor, your chances of being able to fix it without taking on a major project are hit and miss.
What Causes Squeaky Floors?
Floors squeak because something is moving. These are the main culprits.
The edges of sheets of subfloor rubbing against each other because loose nails are allowing the boards to move.
Rubbing between tongue and groove wood that has dried a little over time leaving a gap for movement.
Floor joists shrinking away from floorboards overtime leaving a small gap that squeaks when you put weight on it.
The fix is simple, stop the movement and you will stop the squeak. You stop the movement by nailing or screwing the boards, shimming under the joists or adding bracing between the joists. The challenge is to figure the cause and get access to fix it.
Let's start working from above on a wood floor. If you can't get to the underside of the floor (your squeak is on the second floor or the main floor, but with a finished basement ceiling below), you'll need to work your magic from the top.
With small squeaks, it's likely the floorboards themselves are rubbing against each other, you may be able to eliminate the noise by simple lubricating between the boards. Plain old talcum powder spread along the seam where the boards are rubbing against each may be all you need. Just spreading some talcum powder along the seam and then step on the boards a few times to work the powder down into the seam maybe be enough to quiet the noise.
An alternative lubricant, but one that is potentially much messier, is powdered graphite (NOT the liquid graphite you use to lubricate locks). Again, spread graphite powder along the seam, cover it with a cloth or paper towel, and step on the boards a few times to work the graphite down into the seam. Hopefully that will fix your squeak and you can just vacuum up the residue and forget about your squeaky floor.
If neither of these two options fixes your problem, your next choice is to nail or screw the floorboards more tightly to the subfloor. If you use nails, make them 6d or 8d flooring nails located at least 1/2" from the edge and drive them in on an angle. Predrill holes through the floorboards (but not through the sub floor) slightly smaller then the nail shank. This will help ensure they hold while preventing splintering of the floorboards themselves. Use a nail set to drive the nail heads below the floor surface and fill the hole with color matched wood filler.
You can do the same thing with small finishing head screws as well, and screws do hold better than nails. You'll need to countersink each screw into a counter hole large enough for the head of the screw to be below the floor surface. Specially designed one-piece countersink drill bits are available or you can do this in a two-step process. First, drill your countersink hole and then drill a smaller hole in the center of the countersink hole for the shank of the screw itself. Square head (Robertson) screws are the best choice for this application. Once your screws are installed, you'll need to fill the hole with colored wood filler to hide the screw head.
What About Carpet?
The best option is to roll your carpet back so you have access to the wood underneath. If that isn't an option, you may be able to firm up the floor by nailing right through the carpet. Use a stud finder on the floor to help you locate the underlying joists and then drive nails directly through the carpet into the joists.
Don't try to do this with screws. The twisting screw will get tangled up in the carpet fibers and you'll likely end up with an ugly bare patch on your carpet.
If You Have Access From Below
If you have any cross bracing between floor joists check that it's firmly attached, you'll need to reattach any that have come loose.
A sure way to stop floor movement is to install extra screws through the floor joist up into the subfloor. Drive the screw on an angle (similar to toe nailing) so it passes through the floor joist and up into the sub floor. The fact that it's on an angle will help pull the floor tightly against the joist and prevent the screw from backing out.
Another easy way to stop movement is putting shims in between the subfloor and the floor joists. Just push the shim firmly in place on the top of the joist, don't drive it in or you might raise the floor above and actually cause more squeaking.
Alternatively, you can install "blocking" "bracing" underneath the floor between the joists. Attach a length of 1" x 4" lumber to the subfloor — be sure you don't drive your nails or screws right up through the floor itself, just into the subfloor — and fasten the board to the adjacent floor joists. This extra stability will stop floor movement and should eliminate any squeaks. If the movement is from two sections of sub floor rubbing against each other you could install the 1" x 4" along the length of the seam to hold the edges in place.
A Couple of Things to Help Fix Your Squeaks
Have a helper stand on the floor near where you are installing any nails or screws. Their weight will push the floor closer to the underlying joists. Putting a little construction adhesive on your nails or screws will help them hold better over the long haul.
Your squeaky floors should be a thing of the past with these fixes. No more need to tip toe around to avoid waking up the baby!