The last task that needs to be accomplished before you begin installing hardwood is to lay out tar/felt paper which acts as the underlayment that aids in keeping out dust and preventing squeaks. Most important, it acts as a water-proofer and keeps moisture out
that may seep upwards from below especially if there is a basement directly underneath the area you will be installing hardwood. Do not overlook this step! If water vapor starts to permeate through the bottom of the hardwood floor (which may happen even weeks after it is installed), the floor will raise up in various areas and create an unpleasant wavy appearance. Sadly, the only
way to fix this predicament is to sand the floor down and refinish it. The tar/ felt paper is handy because it is marked with chalk lines which are helpful when attempting to lay it out straight. Be sure to overlap each layer by at least 4 inches, then use your staple gun to fasten it to the floor. After stapling down the tar/felt paper, hammer the staples all the way down so the hardwood can lay as flat as possible against the subfloor.