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How to Install Hardwood Floors: Nail-Down, Glue-Down, and Float (2026)

Installing hardwood floors yourself saves $3–$6 per square foot in labor. This guide covers all three installation methods, subfloor prep, acclimation, layout, and finishing the edges.

Quick Answer

Hardwood floor installation method depends on your subfloor: nail-down is the standard for wood subfloors (plywood over joists), glue-down works on concrete, and floating works for engineered hardwood on any surface. All three methods require 3–5 days of acclimation before installation, a flat subfloor (max 3/16-inch variation over 10 feet), and expansion gaps at all walls. The most common DIY mistake: not letting the wood acclimate to room conditions before installing, which causes gapping or buckling within months.

Frequently Asked Questions

What is the difference between solid hardwood and engineered hardwood?

Solid hardwood is a single solid piece of wood — typically 3/4 inch thick — that can be sanded and refinished 4–6 times over its life. It must be nailed or stapled to a wood subfloor and is sensitive to humidity. Engineered hardwood is a thin wood veneer (1/16 to 1/8 inch) bonded to multiple plywood layers — more dimensionally stable, can be glued, nailed, or floated, and can go over concrete. The top veneer can usually be refinished 1–2 times. Engineered is more versatile; solid is considered more premium and lasts longer in low-humidity environments.

How long does hardwood need to acclimate?

Minimum 3 days, ideally 5–7 days, in the room where it will be installed. Stack the boxes flat or open them and let individual boards lie flat. The room must be at normal living temperature and humidity — HVAC running or close to it. Don't acclimate in a garage or basement if the floor will be installed in a conditioned living space. Wood that doesn't acclimate fully will expand or contract after installation, causing gaps, cupping, or buckling.

Do I need to remove baseboards before installing hardwood?

Yes, for a professional finish. Remove baseboards and reinstall after the floor is done — they cover the expansion gap at the wall and the nail holes in the first course. If you're floating the floor, the baseboard trim hides the expansion gap which is critical (a float floor with no room to move will buckle). Removing baseboards takes 20 minutes with a pull bar and is worth the time.

How flat does the subfloor need to be?

Flatten to within 3/16 inch over 10 feet. Use a long straightedge (8-foot level or straightedge) to check. High spots: sand down (for concrete) or plane/sand (for wood subfloor). Low spots: use floor-leveling compound (for concrete or wood). A wavy subfloor causes the finished floor to flex, squeak, and delaminate.

What direction should hardwood run?

Standard: perpendicular to the floor joists (run the boards across the joists, not along them). This provides structural support and prevents the floor from flexing. Also consider: running parallel to the longest wall in the room makes the room look larger. In a narrow hallway, run parallel to the hall length. Always plan the layout so the last course at the far wall isn't a sliver less than 2 inches — plan rows from center out if needed to avoid this.

Hardwood floor installation method depends on your subfloor: nail-down is the standard for wood subfloors (plywood over joists), glue-down works on concrete, and floating works for engineered hardwood on any surface. All three methods require 3–5 days of acclimation before installation, a flat subfloor (max 3/16-inch variation over 10 feet), and expansion gaps at all walls.

Installing hardwood yourself cuts the total cost nearly in half. The job is sequential — get the prep right and the installation follows.

What you need

Step 1: Prepare the subfloor

For wood subfloor:

  • Secure any squeaky areas with 1-5/8-inch screws driven into the joists.
  • Check for and fix any soft spots (rot).
  • Sand high spots flush with a belt sander.
  • Fill low spots with floor-leveling compound.

For concrete:

  • Test for moisture: tape a piece of plastic sheeting to the concrete for 24 hours. Condensation = moisture problem. Address before installing.
  • Grind down high spots; fill low spots with self-leveling compound.
  • Let compound cure fully per manufacturer’s instructions.

Step 2: Acclimate the wood

Bring the flooring boxes into the installation room. Stack them flat, open the boxes, or separate boards on stickers (small wood strips) for air circulation. Leave for 3–7 days.

Don’t skip this. Record the room humidity and temperature during acclimation — hardwood flooring manufacturers require HVAC conditions to be within normal living range (60–80°F, 35–55% RH) during both acclimation and installation.

Step 3: Plan the layout

Snap a chalk line down the center of the room parallel to the longest wall. Lay out a dry run (no adhesive or nails) to check the last course width. If it’ll be less than 2 inches, shift the start line.

For nail-down: start the first row 1/2 inch from one wall (place spacers at the wall). The first 2–3 courses are face-nailed (near the wall, where the floor nailer can’t reach). After 3 courses, switch to the floor nailer through the tongue.

Step 4: Install underlayment

For nail-down on wood: staple or tape 15 lb. felt or roofing felt across the entire subfloor. Overlap seams by 3–4 inches.

For floating: lay the manufacturer-specified underlayment. Butt seams (don’t overlap) and tape with flooring tape.

Step 5: Install — nail-down method

  1. Start along the chalk line at the starting wall, tongue facing out.
  2. Face-nail the first 2 rows near the wall using a finish nail gun: drive nails at a slight angle into the face of the board, then countersink. Putty later.
  3. Once 2–3 rows are down, use the pneumatic floor nailer. Position the nailer over the tongue at a 45-degree angle and strike with the mallet — this drives a cleat nail through the tongue into the subfloor.
  4. Each board: tap it tight to the previous one, set the nailer, strike.
  5. Stagger end joints at least 6 inches between adjacent rows.
  6. Maintain 1/2-inch expansion gap at all walls (place spacers against the wall).
  7. For the last 2–3 rows: face-nail again where the nailer won’t fit.

Step 6: Install — floating method (engineered hardwood)

  1. Lay the first row along the wall with spacers maintaining 1/2-inch gap.
  2. Apply adhesive to the groove (click-lock systems need no adhesive — just snap the tongue into the groove).
  3. Tap boards together with the tapping block — never strike the tongue or groove directly.
  4. Pull each row tight with a pull bar at the end.
  5. Stagger end joints 8+ inches between adjacent rows.

Step 7: Reinstall baseboards

Reinstall baseboards over the expansion gap. Do not nail the baseboard into the floor — nail only into the wall. The floor must float freely.

Add quarter-round or shoe molding at the base of the baseboard for a finished look.

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  1. Prepare the subfloor and acclimate the wood

    Flatten the subfloor to within 3/16 inch over 10 feet: sand high spots with a belt sander on wood, grind or self-level concrete low spots. Secure squeaky areas with 1-5/8-inch screws into joists. Test concrete for moisture (tape plastic sheeting 24 hours — condensation = moisture problem requiring resolution before installation). Bring flooring boxes into the installation room and stack them flat for 3–7 days with HVAC running at normal living conditions — wood that doesn't acclimate will gap or buckle after installation.

  2. Plan the layout and install underlayment

    Snap a chalk line parallel to the longest wall. Lay out a dry run to check whether the last course at the far wall will be at least 2 inches wide — if not, shift the start line. Run boards perpendicular to the joists. For nail-down: staple 15 lb. felt paper across the full subfloor, overlapping seams 3–4 inches. For floating: lay manufacturer-specified underlayment with butt seams (no overlap) and tape with flooring tape.

  3. Install the first three courses

    Start the first row 1/2 inch from the starting wall (place spacers against the wall for this expansion gap — the floor must be free to expand). Tongue faces out, away from the wall. Face-nail the first 2–3 courses with a finish nail gun at a slight angle, then countersink and fill with putty. The nailer won't fit close enough to the wall for these first courses. Maintain 1/2-inch expansion gap at all walls throughout — use spacers.

  4. Install the remaining courses with the floor nailer

    Once 2–3 courses are down and away from the wall, switch to the pneumatic floor nailer. Position the nailer over the tongue at a 45-degree angle and strike with the mallet — this drives a cleat nail through the tongue into the subfloor without visible nail holes. Each board: tap tight to the previous one with a tapping block, set the nailer on the tongue, and strike. Stagger end joints at least 6 inches between adjacent rows — random stagger patterns look best. For floating engineered hardwood: snap tongue-and-groove joints together using a tapping block; never strike the tongue or groove directly.

  5. Reinstall baseboards and finish the edges

    Face-nail the last 2–3 courses again (where the nailer won't fit) and return to the starting wall to face-nail those as well. Reinstall baseboards over the expansion gap — nail only into the wall, never into the floor; the floor must be free to move under the baseboard. Add quarter-round or shoe molding at the base of the baseboard for a finished look and to cover any small gaps between the floor and the wall.

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