The problem I often hear is that the floors creak and pop a lot. The problem often is that when pressure is applied to the boards, they flex between each other. This means that the tongue is actually moving slightly in the groove and generating the noise. That, plus the boards actually move slightly vertically and rub each other.
Here's something I have done quite successfully on a number of jobs.
Go to a rental store that rents floor nailers. You don't need to rent a nailer but the "cleats" that are for the nailer. They come in a clip all stuck together. Powernailer cleats and Senco cleats that are "L" shaped rather than Portanailer cleats which are "T" shaped work best for this.
Using a pair of wire cutters you can break off individual cleats. You will notice that they are flat and serrated. Using a hammer drive the cleat straight down between the boards so that the flat side of the cleat lines up with the crack in the board. The cleat will go straight down thru the tongue. Set the cleat with a small nail set. The serration on the cleat will help reduce the movement and the shape of the cleat will help it blend into the flooring. A little color putty can make them almost invisible.
The cleats tend to bend fairly easy so so just straighten them back and hit them again. Try to hit them squarely and after a little practice you'll get them in without bending them at all. Put a cleat wherever there is a squeek.
The half inch plywood is most likely not the problem unless is wasn't nailed properly. The flooring could span the joists without the plywood at all. Many old floors have no subfloor with the flooring attached right to the joists.
Usually this problem is a result of someone getting paid to lay a floor by the foot (referred to as Piece Rate). The less nails put in the faster it is to install and the more money for the installer. Adding the cleats as I have suggested will remedy this problem. I have had customers amazed at this "magic trick".
The Polyurethane will work to a certain degree since Polyurethane really is an adhesive. However, I would try the cleat trick first.
I have done the pull and reinstall last resort and while it is time consuming the results are the best.
Call me if you need more information. My cell number is on the website.
Franklyn Gallup
I got into the wood flooring business by accident. By that I mean I messed up a floor royally and when I asked for help I ended up working for and learning from the guy I asked for help.
I have been in the business for the last 30 years as an employee of flooring firms and as a self employed contractor. I now prefer to work as a teacher. My customers become my temporary apprentices and my temporary apprentices become lifetime friends.
I also do online consultation worldwide.
