NWFA certified means a wood flooring professional has been certified by the National Wood Flooring Association (NWFA) in a specific part of the work, such as installing wood floors, sanding and finishing them, or helping homeowners choose a floor.
Classy Flooring ATL installs and refinishes hardwood floors across metro Atlanta and North Georgia, from engineered white oak glued over a concrete slab in Chateau Elan to whole-house refinishing in Hoschton.
What is NWFA certified?
Each NWFA certification is issued to an individual professional, by name, and covers its own part of the work. Three of them cover installing, sanding and finishing, and choosing a floor: Certified Installer, Certified Sand & Finisher and Certified Sales Advisor. NWFA membership is a separate status, and Classy Flooring ATL is an NWFA member company.
Classy Flooring ATL is led by Claudiu Toma, an NWFA Certified Installer, NWFA Certified Sand & Finisher and NWFA Certified Sales Advisor, who completed NWFA Precision Patterns: Parquet Flooring and NWFA Precision Patterns: Medallions. Every project is carried out by our in-house crew.
The NWFA Certified Installer certification covers installing wood flooring; NWFA lists its skills as nail-down, glue-down and floating installation, layout, and patterned floors such as herringbone. NWFA’s installation guidelines recommend that wood flooring be installed to those guidelines and the manufacturers’ instructions by a Certified Installer, an NWFA member, or equivalent, and they call for testing moisture on every job. Wood takes on and gives up moisture with the air and the subfloor around it, so the readings decide when a floor can be installed. In Chateau Elan, 7-inch rift and quartersawn white oak was glued to a slab that read 55 to 65 percent and received two coats of WAKOL PU 280. In Canton, the plywood subfloor read 6.0 percent against the flooring’s 5.5 before about 2,740 square feet of prefinished engineered flooring was installed.
The NWFA Certified Sand & Finisher certification covers sanding and finishing wood floors, with skills NWFA lists as abrasive selection, sanding equipment operation, the finishing process, and repair and maintenance. On a Classy Flooring ATL refinish, the field is sanded with a Lägler Hummel belt sander, the edges along the walls with an edger, and the refining passes with the American Sanders Epoch and FG Floortec Discus planetary sanders, each connected to an FG Floortec dust-control vacuum running through a DUSTIN cyclonic separator. NWFA’s sanding guidelines generally advise against sanding once less than about 3/32 inch (2.4 mm) of wood remains, so the wear layer is checked before sanding: on our Red Oak Atlanta project, the prefinished engineered basement floor measured 4 mm on a leftover box before it was sanded and refinished. In Hoschton, a 20-year-old oil-based finish had turned a warm yellow, and the floor and stairs were refinished with Bona NordicSeal and Bona Traffic HD.
In NWFA’s description, a Certified Sales Advisor explains wood flooring to homeowners and helps them choose the floor that suits their needs. In a Buckhead high-rise, the existing floor was engineered, had been site-finished twice and had no wear layer left for another refinish; it was replaced with 1,500 square feet of solid white oak herringbone, which can be sanded and refinished more times over its life. On the Red Oak Atlanta project, Bona NaturalSeal and Bona NordicSeal were sampled side by side on the existing floor a week before the start, and the clients chose NaturalSeal in person.
A lace-in puts the installation and the sanding and finishing work on the same floor. On a Buckhead home, about 600 square feet of new white oak was tied into about 700 square feet of existing floor, and the whole floor was then sanded and finished as one surface and color-matched to the original. NWFA’s installation guidelines call for replacement boards within 2 percent moisture content of the existing floor.
What are the NWFA wood flooring installation guidelines?
The NWFA Wood Flooring Installation Guidelines, revised in 2025, set out what has to be true before a wood floor is installed and how it is installed: jobsite conditions, acclimation, moisture testing of the flooring and the subfloor, subfloor preparation and flatness, and the nail-down, glue-down, floating and parquet methods. NWFA states that manufacturers’ installation instructions take priority over its guidelines. On Classy Flooring ATL installations, the flooring and adhesive manufacturers’ instructions govern first, and NWFA’s guidelines apply where the manufacturer is silent.
Before the flooring is delivered, the guidelines call for the house to be closed in, the wet trades such as concrete, drywall and painting finished, and the heating and cooling running for at least five days, with the same conditions held before, during and after installation. Where the flooring manufacturer gives no range, NWFA’s general range for solid wood is 30 to 50 percent relative humidity at 60 to 80°F; factory-finished flooring follows its manufacturer’s range. The wood takes its moisture from the house, so the house has to be at living conditions before the wood arrives.
Moisture testing is a standard part of every Classy Flooring ATL installation evaluation, and NWFA’s guidelines say never to install over a known moisture condition and to test so that unknown conditions become known. On a concrete slab, relative humidity is measured inside the slab with an in-slab probe (ASTM F2170). Above the flooring or adhesive manufacturer’s limit, or NWFA’s 80 percent, the installer waits for the slab to dry or installs a Class I vapor retarder per the adhesive manufacturer, and NWFA recommends a Class I retarder on or below grade regardless of the reading. The Chateau Elan slab read 55 to 65 percent and still received two coats of WAKOL PU 280, which WAKOL rates up to 100 percent relative humidity.
On a wood subfloor, the subfloor and the flooring are both measured with a moisture meter and compared. For solid wood, NWFA’s general rule of thumb is a subfloor no more than 4 percent wetter than strip flooring under 3 inches wide, and no more than 2 percent wetter than plank 3 inches and wider. For engineered flooring, NWFA defers to the flooring manufacturer’s moisture, acclimation and installation instructions; in Canton, the plywood read 6.0 percent against the engineered flooring’s 5.5. When the flooring, the subfloor and the room conditions line up and are held there, NWFA’s guidelines allow the flooring to be installed immediately, so acclimation is judged by the readings.
The guidelines set subfloor flatness by installation method, unless the flooring manufacturer specifies otherwise: 1/8 inch in 6 feet or 3/16 inch in 10 feet for glue-down, floating and patterned floors, and 3/16 inch in 6 feet or 1/4 inch in 10 feet for nail-down with fasteners 1-1/2 inches or longer. Every wood flooring adhesive must be elastomeric. At Chateau Elan, the slab was ground, sealed with two coats of WAKOL PU 280, primed with WAKOL D 3045, and brought within tolerance with WAKOL Z 231 self-leveling compound where needed.
NWFA’s guidelines also set what can be installed by grade: engineered flooring on, above or below grade, and solid flooring on or above grade unless its manufacturer allows it below. Both of Classy Flooring ATL’s Buckhead high-rise floors are solid white oak glued over the slab, including the 21st-floor residence.
Claudiu visits every project in person before any work is scheduled. Call Classy Flooring ATL at (770) 401-3659, or use the contact page.