Floors can get squeaky and creaky in any house, generally because of the wood drying out. The dry wood can bring on four different problems: floorboards pulling loose from the sub floor, edges of unevenly placed sub floors rubbing together, floor joists becoming warped and twisted and sub floor nails popping loose from floor joists. Thankfully, the problems involving the sub floor can be solved with some work. If there is a finished ceiling under the floor that needs help your task will be more difficult, and you just might want to settle with having a squeaky floor.
The supplies you will need to fix the sub floor include a helper that will help you find the problem spots, chalk, scrap wood, shims, carpenters glue and screws or nails. You might also need metal angles or cleats and plugs or filler to cover necessary holes in a hardwood floor.
Step One: Go to the basement, or level beneath the floor that needs repair. Have your helper walk around on the upper level to locate the squeaky areas.
Step Two: Mark the problem spots with the chalk. Your help might have to walk around quite a bit, perhaps even bounce in a few locations for you to pin point the exact spots causing the noises.
Step Three: If you notice any locations where the sub floor has separated from a floor joist take a moment and drive a shim into the gap between the joist and the sub floor. If a single shim is not thick enough to fill the space snuggly, then take two or three shims together and drive them all into the space.
Step Four: If there is significant access below the floor, you can also screw the sub floor to the underside of the finished floor where ever boards might have begun to lift or that need some additional securing. This will stabilize the floor.
Step Five: If you chose to secure the sub floor with a metal angle or cleat it is best to start with applying carpenter’s glue on the top of the joist and underside of the sub floor just above it. Then have your helper stand directly above the creak, which will push the floor down to the joist. Attach the cleat or angle to the joist. There is a variety of sizes at your local hardware store to fit a wide variety of needs.
Step Six: If you do not have access to the underside of your floor, you can also countersink screws or nails into the problem boards from the top. Be sure to angle the nails or screws and if more than one board needs securing alternate the direction of the securing hardware. When going this route it is best to plug each of the resulting holes, sand and stain the plug or use a pre stained wood filler and varnish the board(s) to match the rest of the floor.
Step Seven: If the squeak seems to come from sub floor edges rubbing together, a little carpenter glue might be your solution, as long as you have access the sub floor. While standing below the floor, or while working in a crawl space, simply squirt the glue up in through the sub floor seams. As the glue is forced up, it will spread between the floor and sub floor. When the glue dries, you might want to add some more so that the sub floor joists are completely filled.