TIA for any replies:

I recently had 3/4 inch prefinished red oak installed over plywood sub floor, about 1000 feet. It was installed during the summer (90 degree weather in the south) and sat in my house for about 2 weeks before it was installed. It's been installed for about 4 months. I have noticed bad squeaks in the boards, especially in high traffic areas (i.e. in front of refrigerator, opening into kitchen/den). It's not the subfloor; it's comming from the boards rubbing against each other. I called the installer; he came out and looked and said he used enough nails and that the problem is the way the boards are milled.

At any rate, I have been able to silence a couple of spots by comming in from the top with a finish nailer; however, i don't want to do this everytime a new squeak presents itself. I have full access underneath. I thought about using a wide thread screw from the bottom. Does anyone have any experience trying to silence squeaks from the bottom? Would a wide thread screw do the job? If not, could someone recommend a method that might work from underneath?

Thanks very much.

you can screw it down from the bottom just be sure to use a screw thats short enough. To get a squeak there has to be some deflection/movement. It could be in the floor or it could be the subfloor. Ive seen numerous floors where the subfloor plys squeak when they rubbed together or the floor joist had a slight crown and was put in crownside down. while your down there shine a flashlight on one side of the floor joist and see if any light passes through. If you can see some light hammer some shims in there to tighten things up a bit as well.

Thanks, I'll give it a try. I probably have about 4 or 5 spots i'd like to hit. It terms of locating the squeaks from below, i thought about getting some strong magnets (if they even make anything strong enough). I could mark the squeak with painters tape, then tell my wife to yell when the magnet is over the tape. I could move the other magnet from below. Does anyone else have any suggestions on this?

You can also use these to check the nailing schedule of the installer. http://www.magnet4sale.com/Sphere-neody ... b-Magnets/

Sounds like bad milling.
There should not be slop between the T&G joint.

A cracked tongue can do just what you described and the associated noise.

From underneath is the best way to address squeaks. Use a combination of shims and short enough screws.