Both finished and unfinished hardwood flooring boards, whether they are engineered or solid hardwood, have interlocking tongues and grooves, and you install them on a wood subfloor by nailing through the tongues. You need a manual or air-assisted flooring nailer for this -- both these tools operate in the same way, but an air-assisted nailer requires less effort on your part.
Before you lay lines or begin laying out boards, make sure you've leveled the subfloor and covered it with a protective moisture barrier. Acclimate the flooring by spreading it around the room and leaving it out until its moisture content is within 4 percent of that of the subfloor -- usually three to five days.
Step 1: Choose the starting point.
In most cases, the best place to begin installation is along a wall that runs in the direction of the flooring. Some circumstances, however -- such as extending the flooring through a doorway or installing in a irregularly shaped room -- call for beginning along a line drawn down the middle of the floor.
Step 2: Draw a line.
Snap a chalk line along the wall or in the middle of the floor. When you're starting next to a wall, the line should be a uniform 1/4 inch away from it. If it's in the middle of the floor, the line should extend straight from the main point of entry or some other prominent feature. When laying a line in the middle of the floor, don't simply follow a wall -- the wall may not be straight.
Step 3: Install the first row.
Lay boards along the line with their groove sides facing the line, and tap them together end-to-end. Cut the last board in the row to fit, using a circular saw or a chop saw. Face-nail the boards to the floor by drilling pairs of 1/8-inch holes in them at 6-inch intervals and driving a 2-inch finish nail into each hole with a hammer. Set the heads with a nail set.
You need to lay two rows if you start in the middle of the floor. Cut 1/4-by-1/4-inch splines from scrap wood to fit in the grooves, and install these rows with their tongues facing outward.
Step 4: Rack the boards.
Assemble several rows of flooring without nailing them to ensure color uniformity. Stagger the ends of the boards in each adjacent row at least 6 inches from each other, and keep the stagger pattern as random as possible. Avoid such racking mistakes as steps and H's, which are formed by matching joints at the ends of boards in nearby rows.
Step 5: Nail the boards.
Tap each board into place using the beveled end of the mallet that comes with the flooring nailer. Once they fit tightly together -- you may have to pry some to get them to fit -- drive 1 1/2- to 2-inch flooring cleats through the tongues with the nailer, spacing them by 8 to 10 inches. Reduce the spacing to 6 to 8 inches for planks wider than 3 inches.
Step 6: Cut notches with a jigsaw.
Cut notches and curves around posts, doorways and cabinets using a jigsaw. To prevent surface chipping, lay masking tape along the cut line, and then mark the line on the tape and cut through the tape.
Step 7: Rip boards for the last row.
Measure the width of the final row at both ends of the wall, using a tape measure, and rip the last flooring board to create a gap of between 1/4 and 1/2 inch. If the wall isn't straight, you may have increase the width of each board in that row to avoid leaving a space you can't cover with baseboards. Rip the tongues off the boards in that row, using a table saw, and then set the blade depth to half the thickness of a board and rip the bottoms off the grooves.
Step 8: Install the last row.
Lay each board into the gap and face-nail it, using the same technique you used to face-nail the boards in the first row.
After You're Done
If your flooring boards are prefinished, you simply need to fill the nail holes with wood putty and the installation is complete. If the boards are unfinished, you still have several days of work ahead of you filling, sanding, staining and finishing the floor.