There are many types of hardwood flooring available, ranging from prefinished, laminated (also called engineered) strips and planks. In other words, everything from thin plywood with a hardwood veneer layer on top, to solid-wood strips and planks. In the past, if you wanted to install your own solid-wood flooring you also had to take on the task of sanding and finishing it. Today you can get solid-hardwood flooring prefinished in a variety of stain colors with a durable, long-lasting factory-warranted finish.
Like unfinished hardwood floors, the prefinished types typically have tongue-and-groove edges on all sides. They are available in 3/4-inch thickness, as well as low-profile styles that are 5/16- to 5/8-inch thick, which are a good or installing over existing flooring. Solid wood floors should not be installed in basements or below grade. Thinner styles can be glued to the sub-flooring. Full-thickness floors are installed using a special nailing tool that locks each strip tightly against the previously installed strip and, in the same motion, inserts a cleat nail or narrow-crown staple through the tongue joint into the sub-flooring.
Be careful to avoid damaging the finished surface during installation. Otherwise, installing prefinished hardwood is no more difficult than installing unfinished strips. Both require some carpentry experience.
Measure the width and length of the room and multiply the two numbers to get the square footage. When ordering flooring, add an extra 10 percent to allow for cutting and fitting. If you run short and have to order more, you could get wood from a different lot that’s not an exact match in color or size.
Stack wood in the room where it will be installed for one to two weeks prior to installation. This will give the wood time to acclimate to your home's climate. If the house is newly constructed, be sure the room is continually heated or air-conditioned to a normal, occupied temperature.
This flooring can be installed over old wood flooring or over a plywood sub-floor. A minimum 3/4-inch-thick sub-floor is required. If you are working atop a single plywood layer, we recommend adding a second layer of 1/4- to 1/2-inch plywood or commercial floor substrate material.
Use wood or drywall screws to attach the substrate to the floor joists. At this stage, you want to eliminate any squeaks in the floor. If you locate a squeak, run a long screw through the sub-floor and into the joist below it.
Remove any base or shoe molding around the perimeter of the room. Vacuum the floor and block doorways to keep dirt and foreign objects out of the work area. Even a small bump can ruin a level floor installation.
You’ll need a continuous vapor barrier beneath the flooring. Asphalt-saturated #15 felt (tar paper) is usually recommended. If moisture is not a problem, use red rosin paper as a “slip sheet” between the flooring and sub-flooring. It will reduce or eliminate floor squeaks caused by friction between the wood layers.
Roll out the paper and overlap edge of each sheet at least 4 inches. Flatten out any bumps or wrinkles, and use a heavy-duty staple gun or staple tacker to attach the paper to the sub-floor.
Manufacturers recommend installing hardwood flooring perpendicular to, or across the floor joists for maximum stability and reinforcement. But typically, flooring installed parallel to a room’s longest dimension is more attractive than when installed across the floor’s shorter width. Also, it’s easier to keep rows parallel if you begin at an unobstructed wall and install long, straight rows.
Nailing the flooring into the floor joists will also help with stability. If you choose a perpendicular layout, mark the location of the floor joists along the baseboards — typically 16 inches on center (image 1). Floor vents are normally attached to joists, so you can use that as a starting point for measuring. Snap a chalk line across the room at each joist marker (image 2).
All wood floors expand and contract, so you must leave a gap around the perimeter of the room. Typically, the gap is about a 1/2 inch. The width of the gap is determined by the length of the run and the type of wood. Solid wood needs a bigger gap than engineered wood because it expands and contracts more. Measure and mark 1/2 inch out from each wall, plus the width of the first board, and use a chalk box to snap starter lines.
Lay out several rows of loose boards along the length of the floor, following your plan. Mix boards from several bundles to avoid noticeable color changes from one bundle to another. Arrange lengths, wood-grain patterns and variations in board colors to create a balanced look. To avoid confusion when installing random-width strips or planks, lay out the boards in alternating courses based on width.
Choose long boards for the first row and align them along your chalk line with the board tongues facing out toward the center of the room (image 1). Place the first board in the row so that its groove end aligns with the chalk line at the end wall. Be sure there is a 1/2-inch gap between this row and both the side and end walls.
The first row needs to be face nailed. To prevent the wood from splitting, drill pilot holes along the gap edge every 10 to 12 inches then top-nail the starter course with 10d finishing nails (image 2). Try to make sure they go through the sub-floor and into the floor joists. Use a nail set to sink the nail heads slightly below the wood surface (image 3). Secure this row by blind-nailing or stapling through the tongue joint with the power nailer.
After the first row is firmly attached, begin at one end and use the power nailer to install the next row of boards (image 4). If the boards don’t fit together easily, use a mallet with a scrap piece of flooring as a tapping block to knock them into place (image 5). Be careful not to damage the edges or board surfaces. Install one complete row at a time from end-wall to end-wall. Place at least two nails in every board — the rule of thumb is to nail every 10 to 12 inches.
Flooring is typically bundled in random lengths. Vary board lengths as you install so you will have staggered end-joints in a random pattern (image 6). Avoid repeating patterns — a repetitive joint pattern can result in a weaker floor. Installers recommend staggering end-joints a minimum of 6 inches for narrow-strip flooring, 8 to 10 inches for planks that are up to 5 inches wide, and 10 inches or more for wider planks. When a row approaches an end wall, select final pieces that will be a minimum of 12 inches long. Don’t forget to leave a 1/2-inch gap at the wall. Measure and cut off the ends, then use these cutoffs — with their tongues or grooves intact—as starter pieces for the next row.
Do not attempt to cut boards to length within the floor pattern. Flooring strips have chamfered edges to help them lay flat where they meet. Cut boards to fit only at the end of a row where refinishing the board ends is not necessary.
Make sure each board is locked tightly against the preceding row, because even a small gap can cause the entire floor to be off. Any variation must be corrected when and where it appears. Gaps between boards can be caused by misalignment, poorly milled edges, wood splinters in the grooves and other obstructions. If you have a gap, pry out and discard the board, eliminate the damage or obstruction and reinstall a new board.
When installing up to a threshold, it is not critical to cut each row’s end to an exact length. After the floor is complete, you can use a circular saw to cut across the ends for a precise fit.
As you near a wall or other obstacle, clearance for the flooring nailer may be restricted. Where necessary, drill pilot holes and hand-nail the boards, blind-nailing through the tongue joint if possible, or face-nail and set the nail heads below the board surface.
Where the final row meets the wall, it may be necessary to rip boards lengthwise to fit. Narrow end boards are usually hidden by base molding.
Use wood putty to fill holes where boards have been face-nailed and to touch up any minor installation damage or marks. Be sure to buy putty that will accept stain or match the color of the finished floor. Prefinished flooring manufacturers typically offer touch-up products specifically matched to the flooring you choose.
Finally, paint or stain and install base molding to trim out the walls around the room. Be sure the molding completely covers the expansion gap on all sides.