Stop the Squeaky Floor and the Door That Won't Shut

A floor squeaks because two things are rubbing that shouldn't be. Usually it's a nail shank sliding in and out of a hole in a joist while you step on it and off it. Sometimes it's two hardwood boards grinding at the tongue. That's the whole mystery. Once you know which one you've got, the fix takes twenty minutes and costs less than a pizza.

Start under the floor if you can get there. Send someone upstairs to walk the bad spot back and forth while you stand in the basement with a flashlight and watch the subfloor move. You'll see it. A hairline gap opening and closing between the top of the joist and the underside of the plywood, right where the footstep lands. Mark it with a pencil.

The shim, and the one way people wreck it

Take a cedar shim, butter the thin end with wood glue, and slide it into that gap. Snug. Then stop.

Don't drive it. The temptation is to give it two good taps with a hammer and really wedge it in there, and what you've just done is lift the floor above into a small hump and create a brand new squeak eighteen inches away. The shim fills the gap. It doesn't lift anything. If you can pull it back out with your fingers before the glue sets, that's about right.

For a long complaining stretch rather than one spot, run a bead of construction adhesive along both sides of the joist where it meets the subfloor and add short blocks of 2x between the joists, screwed to the joists and pushed tight against the subfloor. Adhesive does the quiet work here. Screws just hold it while it cures.

Screwing from below, without a screw tip in your bare foot

If the finish floor has pulled up off the subfloor, you can pull it back down from underneath. Measure first. Three-quarter-inch plywood subfloor plus three-quarter-inch hardwood is an inch and a half of material, so a 1-1/4 inch screw grabs plenty and stops a quarter inch short of daylight. Pre-drill through the subfloor with a bit slightly larger than the screw shank so the screw spins free in the plywood and pulls the hardwood down instead of jacking the two apart.

Have your helper stand on the spot while you drive it. Their weight closes the gap, the screw holds it closed.

Before you drill anything blind, know what's under there. Radiant heat tubing, low-voltage wire stapled to the joist face, a copper line run tight to the subfloor. A flashlight and thirty seconds of looking beats a call to a plumber on a Sunday.

When the only access is from the top

Carpet is the friendly case. The scored-screw kits sold for this at any hardware store come with a depth-control fixture that sits on the carpet, lets you drive the screw through the pile into the joist, then snap the head off below the surface. The pile closes over it. Find the joist first with a stud finder, or by tapping. Screwing into nothing but subfloor buys you about a week.

Hardwood is the unfriendly case, because the honest fix is visible. A trim-head screw driven through the face of the board into the joist, countersunk, filled with matching putty. It works permanently. It also leaves a small dot in your floor forever, and in a wide-plank white oak living room that dot will be the only thing you look at for the rest of your life. Think about it before you drill.

Baby powder or graphite worked into the seam between two grinding boards is the low-commitment move. It quiets a board-on-board squeak for a few months. It does nothing at all for a loose subfloor, so if the powder doesn't help, you've at least learned what the problem isn't.

Stairs are their own animal

Stair squeaks live where the back of the tread meets the top of the riser. If the underside of the staircase is open, glue and screw triangular blocks into that corner from behind and you're done, invisibly. Most staircases aren't open, which leaves you working from the front: pilot a hole down through the tread into the riser, drive a trim-head screw, fill it. Two screws per tread, not six. You're stopping movement, not building a bridge.

Now the door

Close it slowly and watch where it touches. Nine times out of ten it's binding at the top corner on the latch side, and there's a shiny worn stripe on the jamb telling you so. That's not a swollen door. That's a sagging one.

A door hangs off three screws in the top hinge, and the factory ships that hinge with three-quarter-inch screws that bite nothing but the soft jamb. Over a few thousand slams, the jamb gives up. Back out the center screw from the jamb leaf of the top hinge, pre-drill deeper, and drive a 3-inch screw through the jamb, through the shim space, into the framing behind it. Snug it gradually and watch the top of the door lift away from the jamb as you go. That single screw fixes more sticking doors than every other trick combined.

If the screw hole is chewed out and the screw just spins, jam the hole full of wood glue and bamboo skewers or a golf tee, snap it off flush, let it dry an hour, and drill fresh. Toothpicks work too, but they're a stopgap. Use something with some meat.

Latch won't catch

Color the latch bolt with a marker, pull the door shut against the strike plate, and open it. The mark tells you exactly which way the plate needs to move. A quarter turn with a round file on the strike opening handles a sixteenth of an inch. More than that and you're better off unscrewing the plate, plugging the holes, and remounting it a hair over, then chiseling the mortise to match.

Actual swelling, and the mistake to avoid

If a door only sticks in August, don't plane it. Sand it in August and you'll have a gap you can read a newspaper through in February. Live with it, or take the door off, seal the top and bottom edges with primer, and rehang it. Bare end grain on a door edge drinks humidity like a sponge, and half the doors in America have never been sealed there.

When you genuinely do need to remove material, pull the door, lay it on sawhorses, and work the edge with a sharp block plane or an 80-grit sanding block. Take an eighth of an inch max, keep the slight bevel on the latch edge, and prime whatever bare wood you exposed before it goes back up. A solid-core door runs 60 pounds or more. Get a second set of hands, or you'll find out how a hinge pin feels against a knuckle.

The point where this stops being your job

Three doors sticking in the same season is weather. Three doors sticking on the same wall, plus a diagonal crack running off the corner of a door frame, plus a floor that reads out of level to a marble, is movement. Put the plane down and call an independent structural engineer, one who doesn't also sell piers.

Same answer if the floor feels springy rather than squeaky, or if you get down there and find a joist somebody notched halfway through to run a drain line. That's not a squeak. That's a beam doing a job it's no longer sized for.

A house that squeaks is talking to you. A house that sticks in three rooms at once is telling you something that costs real money, and the sooner you listen, the less of it you spend.