Solid wood and engineered flooring may be installed using1a nail-down installation method. The flooring is attached to a tongue and groove plywood or wooden subfloor using nails or staples. This method of installation is typically not used below grade because the subfloor is usually concrete. Please note that regardless of installation method, 3/4" solid wood flooring should not be installed below grade.
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The boards are attached to the subfloor using either a manual or pneumatic nailer. The edge of the nailer is placed against the tongue of the board and the plunger is hit with the mallet. That snugs the two boards together and drives a two-inch nail cleat through the tongue and into the subfloor. Whenever possible, it is best to use this method of installation when installing hardwood flooring.

Please read complete manufacturer's instructions before you begin. This will insure proper installation.