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Figure 5-10: (C) J Wiley, S Bliss Best Practices Guide to Wood Floor Installation

  • FLOOR, WOOD INSTALLATION GUIDE - CONTENTS: Flooring, solid wood strip & plank installation procedures: details. Subfloor Specifications for Solid Wood Flooring Installations. Guide to Installing Solid Wood Flooring Over Concrete. Guide to Nailing Solid Wood Flooring: Nailing Specs. Installing wood flooring over radiant heat, guide. Where to buy wood flooring products for building interiors: manufacturers, wood flooring industry associations
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How to install wood flooring:

This article explains the best practices used when installing wood flooring in buildings, including installation details for different surfaces: concrete, underlayment, etc.

This article series discusses and provides a best construction practices guide to the selection and installation of building interior surface materials, carpeting, doors, drywall, trim, flooring, lighting, plaster, materials, finishes, and sound control materials.



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Installation Procedures for Solid Wood Flooring

Figure 5-8: (C) J Wiley, S Bliss

As described in the book, Best Practices Guide to Residential Construction Chapter 5, Interior Finish:

Standard 3/4-inch strip or plank flooring is nailed through the tongue into a sound, dry wood subfloor—either plywood, oriented-strand board (OSB), or solid planks. If installed over a slab, the subfloor can either be floated or nailed to the slab.

[Click to enlarge any image]

Subfloor Specifications for Solid Wood Flooring Installations

In new construction, the best subfloor for wood flooring is nailed and glued 3/4-inch T&G plywood, with the finish flooring installed perpendicular to the joists if possible.

Research conducted by the National Oak Flooring Manufacturers Association (NOFMA) has shown that 5/8-inch plywood or 3/4-inch OSB also have adequate nail-holding ability for hardwood flooring, although OSB can swell if it gets wet.


Before installing the flooring, nail or screw any loose spots, and shim or sand down any uneven spots to prevent squeaks.

Then lay down a layer of 15-pound asphalt felt, which reduces the flow of water vapor into the flooring. The added friction also helps restrict movement in the flooring.

Leave a 3/4-inch expansion space along the edges on the long side of the flooring to accommodate any movement.

The expansion space can be concealed with baseboard and shoe molding or by cutting back the drywall (Figure 5-8).

Guide to Installing Solid Wood Flooring Over Concrete

For below-grade installations, use a laminated flooring product. For slabs-on-grade, a plywood subfloor is required—either nailed to the slab or floated on top. The slab should be poured over granular backfill with a vapor barrier and must be dry before installation.

To test for dryness, duct-tape a one-square-foot piece of polyethylene film to the floor for 24 hours. If the film is clouded or beaded up with moisture, the slab is too wet. Slabs less than 60 days old are usually too wet. Use heat and ventilation, if necessary, to speed up the drying time.

The slab should be level to 1/4-inch in 10 feet. Level any uneven spots with clean mason’s sand or a floor leveling compound. Next, lay down a 6-mil polyethylene vapor barrier.

Figure 5-7: (C) J Wiley, S Bliss

On a dry slab where moisture problems are not anticipated, the nail-on method is preferred.

Nail 3/4-inch plywood to the concrete with powder-actuated fasteners using at least nine nails per panel (Figure 5-9).

Leave 1/4 to 1/ 2-inch between sheets and 1/2-inch around the room perimeter for expansion. Start alternating courses with half sheets so the joints are staggered.

Lay 15-pound felt over the plywood and install the flooring. To avoid puncturing the vapor barrier and hitting the concrete, use shorter 1 3/ 4-inch flooring nails or an angled adapter on the floor nailer.

Figure 5-10: (C) J Wiley, S Bliss

If there is any question about moisture coming up through the slab, use the floating method (Figure 5-10).

As an extra precaution, tape the laps in the poly vapor barrier and run it a few inches up the wall. Next lay down, but do not nail, 4x8 sheets of 1/2 -inch plywood with the long edge oriented along the length of the room. Leave a 1/4- to 1/2-inch gap between sheets and 3/4- inch around the room perimeter.

Next, lay another layer of 1/2-inch plywood oriented at 45 degrees to the first layer with the same spacing, and staple, screw, or nail (7/8-inch ring-shank nails) the top layer to the bottom, being careful not to puncture the vapor barrier. Finally, cover the plywood with 15-pound felt and install the flooring.

To insulate the floor, a layer of compression-rated foam insulation can go between the poly vapor barrier and the plywood.

Guide to Nailing Solid Wood Flooring: Nailing Specs

In general, the more nails in wood flooring, the less likely there is to be movement or squeaks. The recommended nailing schedule for 3/4-inch-thick strip flooring is every 8 to 10 inches with a 7d or 8d flooring nail (see Table 5-5). If the subfloor is less than 3/4-inch thick, nail into the joists with one nail between each joist. Stagger the ends of strip flooring at least 6 inches.

Table 5-5: (C) J Wiley, S Bliss

For plank flooring 4 inches and wider, the minimum nail spacing is 8 inches; closer is better.

With boards over 5 inches wide, if the ends are not end-matched (with T&G), the ends will tend to cup or curl unless face-nailed or screwed and plugged with two to three fasteners.

It is also a good idea to secure the flooring along its length with face-nails or screws and plugs.

If nailing, use wedge or screw-shank flooring nails set below the surface, or decorative nails left exposed for a traditional appearance.

Drive the face nails about 30 degrees away from the center to help reduce cupping. Use two to three nails across for planks up to 5 inches, three to four nails for planks up to 8 inches.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Resources: Manufacturers, Industry Associations, & Sources of Indoor Wall Materials, Flooring, Carpeting, Lighting, Sound Control Materials

Prefinished Wood Flooring

Bamboo Flooring Producers & Sources

Resilient Flooring Manufacturers List

Cork Flooring Manufacturers & Sources

Polymer (Urethane), MDF, and Vinyl Trim Producers & Sources

Flexible Trim Manufacturers & Sources

Wood Flooring Industry & Trade Associations for Wood Products, Flooring and Floor Installation

-- Adapted with permission from Best Practices Guide to Residential Construction.

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