Squeaky Wood Floor Requires Access To Floor Joists


I just bought a 32 yr. old house and the hardwood floors squeak. Is there a way to fix this?


Dear Lou

Yes there is but it will not be easy. The three wood members; joist, subfloor and finished hardwood have separated, and the nails binding them now are moving in the loosened nail holes.

This separation is generally caused by seasonal shifting of the boards, and you would be well advised to keep the indoor relative humidity levels to about 40-60%. I mean all year round. And sadly some hardwood floors were poorly nailed in the first place.

If you can access the floor from under the joists you can try a nifty new product called Squeak-Ender at http://www.squeakender.com. They have several well-engineered solutions to squeaking and sagging floors, and it worth checking out. These products will save you from having to nail from the top of the floor, for the most part. The Squeakender’s web site has excellent illustrations of these products, so I needn’t explain further. You may however have to use some of the next described methods if these products are only somewhat effective.

But with second floor squeaks and lack of access to the floor joists on a main floor just how can you re-nail a hardwood floor?

You will need to find the joist that runs under the subfloor, so that when you re-nail the hardwood, it will pull the board down and stop the squeak. This method as you can imagine works best when the finished hardwood boards run at right angles to the joist.

First find the where the joist run by removing the quarter round molding from the edge of the floor. Only remove the molding running at right angles to the joist. Drill a 1/4″ hole in this space (that the molding will cover) and insert a bent coat hanger. In either direction you will feel the hanger bump up against the joist. Measure over and drill another hole closer to the joist and test again, until you have determined the center of this joist. Do the same on the opposite side of the room, and snap a chalk line between the two. This should represent the run of the floor joists. They should in most modern houses run every 16″, but you may have to drill more edge holes to confirm this. If the room is wider than 15 feet, there may be a supporting beam separating two separate runs of joists. And they may not line up with each other across the room. You can only see this from below, even if you have to poke a small view hole in a basement ceiling.

If you are unlucky enough to have the hardwood running in the same direction as the floor joists, you will only be able to re-nail one strip of hardwood every 16″ (as the joists are spaced). This will quiet a squeaky subfloor, but you may have to nail between the joist with 2″ finishing nails in a attempt to quiet the loose hardwood in between the joists.

Once you have marked out all the joists with the chalk line, determine which side of the hardwood strips is the tongue side. You will want to pre-drill or nail spin (nail spinners are a must at www.leevalley.com; Prod. #99K20.01) a 3″ spiral finishing nail, so that this nail goes through the tongue side of the hardwood floor through the subfloor, and penetrates the joist quite solidly. This 3″ nail is only used for 3/4″ thick floors, use shorter ones for thinner strip floors. Use 2 1/2″ for 1/2″ hardwood and 2″ for the thin 3/8″ strip floors.

Modern floor joists are less than 2″ wide so they are easy to miss, and you can tell when you are hitting the joists when the nails feels solid all the way in. Set the nail below the surface with the proper sized nail set, and fill with a colored putty. Use a colored latex putty that will dry hard if you plan on sanding the floor now. But use a soft, non-drying colored putty and wipe off the excess with odorless mineral spirits, if you want to keep the floor finish intact. Choose a color just slightly darker than the finished wood.

You can do this re-nailing every sixth board or so and see how it works. Then put more nails between these if you need to. Don’t over do it, or you will have a really pock marked floor.