Renewing Existing Wood Floors

Renewing Existing Wood Floors

By Brett Miller, NWFA Vice President of Education & Certification

Any installer who measures the success of his or her business by only new installations is missing a large potential profit. Besides new installations, there is an even larger wood flooring market out there that can have a big impact on your flooring business – the hundreds of thousands of square feet of wood flooring already installed.

It is not necessary to fully sand the floor to restore the finish. Abrade and recoat may suffice.
It is not necessary to fully sand the floor to restore the finish. Abrade and recoat may suffice.

All of those existing wood floors represent a potential windfall for your company through refinishing jobs. In fact, according to the 2016 US FLOOReport, about 60% of all wood flooring sales can be attributed to refinishing existing wood floors. Think about that…more than half of all wood flooring sales are a direct result of work performed on wood floors that were already installed. Is this a market your business is pursuing?

One of the significant selling points for wood floors is that they can be renewed time and time again, but when the floors have changed hands numerous times, the homeowner may have no idea what type of finish is on the floor. As a wood flooring professional, you know this information is essential to the refinishing process.

Here’s how can you determine what the existing finish is before starting your work. First, you will need to determine the age of the structure. If it was built before 1978, there is a possibility that the wood floor finish contains lead. Federal law requires that wood floors be tested for lead in structures built before 1978. Test kits are available to determine the presence of lead in floor finishes and other architectural coatings. You must also abide by local, state and federal guidelines for the handling and disposal of lead-based products. Failure to do so can result in significant fines ranging into the tens of thousands of dollars, so be sure to become familiar with the laws in your area by visiting the U.S. Environmental Protection Agency website,

There also are simple tests you can conduct to determine the type of finish on an existing floor. To determine if the floor has a surface finish, scratch the floor gently with a coin in an inconspicuous area. If the finish flakes, it likely is a surface finish. Another way is to apply two drops of water in an inconspicuous area. If white spots do not appear within 10 minutes, it’s likely a surface finish.

To identify wax finishes, use a small amount of mineral spirits on a clean, white rag in a low traffic area. If the rag appears slightly yellow or brown, the floor likely has a paste wax finish. To identify acrylic waxes, mix a small amount of dish soap, ammonia and water, and place a drop in a low traffic area. If the spot turns white, it’s likely an acrylic wax finish.

Once you’ve identified the finish type, you should start a daily job log. Record all information, including number of square feet, the weather, the condition of the floor, moisture contents, color notes if staining the floor, finish notes including amount used, name brand and lot numbers, dry times between coats and amount used in each coat.

It is not necessary to fully sand the floor to restore the finish unless the floor has visible dents, wear patterns or permanent cupping, or the customer wants to change the color of the floor. Abrade and recoat may suffice.

The number of times a given floor can be sanded depends on the skill of the person sanding the floor, the type of equipment used, the thickness of the remaining wear layer, and the flatness of the floor. Refer to the floor manufacturer’s guidelines on the number of times a floor can be sanded, and for any other recommendations.

Further, you’ll need to evaluate wear layer thickness in several areas and check for flatness to ensure whether you should attempt sanding. Measurements can often be made at floor registers or by removing transition moldings. Where there are sufficient gaps between boards, a feeler gauge may be used to measure the thickness of the flooring down to the tongue. Note that this method works well with solid wood flooring, but may not be accurate with some engineered flooring. The wear layer on some engineered wood flooring may not be as deep as the tongue. Generally, if the wear layer thickness is less than 3/32“, then the floor should not be sanded.

High-abrasion finishes such as aluminum oxide may be difficult to sand. These types of finishes may respond better by using a fine-grit abrasive such as an 80-grit or finer grit ceramic-fired abrasive for the first grit used, followed by a coarser grit to begin the upward grit progression to remove these surface finishes.


When sanding eased- or beveled-edge flooring, the appearance of bevels may not be consistent after sanding. In the case of a micro-bevel product, it is possible the bevel will be eliminated. The sanding process may require an extra cut in order to completely eliminate these eased edges. When maintaining the beveled edges, carefully clean and/or scrape the bevels, being careful not to damage the face of the board. In addition, make the customer aware that sanding a beveled-edge product will change the profile of the bevel and the look of the floor. If the floor was previously site-finished, then use the least coarse abrasive necessary to remove the previous finish.

When resanding a dark-stained or white-stained floor and changing color, the floor can exhibit residual stain in the soft grain and cracks, which may require a more aggressive first cut in order to remove the previous color. Older installations that undergo the refinishing process also may experience filler-pop. This is the result of wood flooring’s movement.


Pre-existing conditions, such as loose substrates or vertical deflection in the flooring system, may cause wavy or chattered appearances in the final sanded product, and are often unavoidable.

Pre-existing conditions may cause wavy or chattered appearances in the final sanded product.
Pre-existing conditions may cause wavy or chattered appearances in the final sanded product.

It may not be possible to completely alleviate the effects, but it may be possible to minimize them. Try sanding the floor at a 7- to 15-degree angle all the way through the final sanding phases. This requires additional sanding with a multi-disc, planetary or oscillating machine to properly remove scratch marks in the flooring surface and remove the condition. Then, secure the substrate from below per local building codes.


There are many other potential issues that should be considered when sanding and refinishing existing wood floors. These situations are addressed in detail in the recently revised NWFA Wood Flooring Sand and Finish Guidelines. These Guidelines are provided to all NWFA members as a member benefit. They are available to non-members for purchase. For more information, contact the NWFA at (800) 422-4556 (USA and Canada), (636) 519-9663 (international), or

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