Wood Flooring Grades
Following National Wood Flooring Association’s (NWFA) guidelines, unfinished domestic hardwoods, such as White Oak, Red Oak, and Hickory, are graded on appearance. Prefinished hardwood, on the other hand, is based on a manufacturer’s descriptions, which are mostly for marketing.

When you are looking to buy unfinished wood flooring, your hardwood floor will be categorized into one of the following grades:

Clear – Has a uniform appearance primarily composed of heartwood.
Select – Almost as uniform as Clear but with some natural characteristics.

1 Common – Has more color variety, some mineral streaks, and knots.

2 Common – Greater color variation and natural marks.

3 Common – Value flooring with distinct natural marks.

Maple is an exception. If you want to add unfinished maple hardwood to your home or building, a similar range of quality is described by the following terms: First, Second, and Third. Contemporary terms Select #1 and Select #2 may be used instead.

Wood Flooring Construction – Solid vs. Engineered
Solid Hardwood Flooring
Considered the highest-quality flooring, unfinished solid hardwood is the oldest form of wood flooring and comes in longer plank sizes than prefinished and engineered types. Solid hardwood flooring is used with wood subfloors or is created with a floor joist system. Unfinished solid flooring is nailed or stapled into place and sanded, and then a finish is added.

As with any type of unfinished flooring, unfinished solid hardwood offers several design possibilities with stains. Rather than going off color samples (the typical procedure for prefinished flooring), you can test different stains in your home and find which one works best with the space. Once you have found the best stain, all test spots can be sanded down. Solid flooring can be sanded a nearly-unlimited amount of times.

Solid flooring offers more variation than other types of wood floors. In addition to longer plank sizes, unfinished solid flooring is manufactured in thinner strip sizes. Typical solid flooring is 3/4ths of an inch to one inch thick and is 2.25 inches wide. Width can go up to five or seven inches, depending upon the brand. A piece of unfinished hardwood, however, may be as thin as 5/6ths to one-half of an inch and 1.25 inches wide.

Engineered Wood Flooring
Able to be installed above, on, or below grade, unfinished engineered flooring expands and contracts less compared to solid hardwood when exposed to moisture and heat. In order to achieve this, engineered flooring manufacturers put together three to nine separate layers of hardwood, with the grain on each facing a different direction.

This type brings together the design possibilities of unfinished hardwood with the versatility and ease of installation engineered floors have. Unfinished flooring, in general, offers many finish possibilities and provides a greater area for testing a stain. This way, you do not need to go off the color samples for prefinished flooring, and you can find the right match for your space.

Unfinished engineered floors have certain assets and downsides depending upon need. Unfinished flooring general blends in better with existing hardwood, but the installation process is significantly longer than that for prefinished flooring. Finishing can take weeks and the space needs to be fully clean and isolated.

All About The Janka Hardness Test
To determine the overall hardness of a particular wood species (domestic or exotic), the wood flooring industry uses the Janka hardness test. The test itself measures the force required to embed a 0.444″ steel ball into half its diameter into a piece of wood. The higher the rating, the harder and more dense the wood. While ratings do vary based on various environmental factors, they do help to gauge a particular species’s ability to withstand wear and denting; an important factor when determining how a wood floor will most likely perform under normal wear and tear conditions.

As the chart details, by and large, exotic woods dominate this test with many South American species like Brazilian Walnut and Brazilian Teak offering some of the most dense wood floors on the market.

Domestically, North American Hickory wins as the hardest wood species used to manufacture hardwood flooring. Of note, White Oak and Red Oak are great options to consider for projects requiring installation of a wood floor over radiant heating systems.

The corresponding chart contains a wide range of species to compare for reference.

Brazilian Ebony
3692
Brazilian Walnut
3680
Bolivian Cherry
3650
Lapacho
3640
Brazilian Teak
3540
Tiete Chestnut
3540
Tiete Rosewood
3280
Brazilian Redwood
3190
Brazilian Rosewood
3100
Bloodwood
2900
Patagonian Rosewood
2800
Brazilian Cherry
2350
Carribean Rosewood
2300
Santos Mahogany
2200
Tigerwood
2160
Purple Heart
2090
Merbau
1925
Amendoim
1912
Hickory/Pecan
1820
Bolivian Rosewood
1780
Doussi
1770
Kempas
1710
Bamboo
1650
Wenge
1630
Zebrawood
1575
Timborana
1570
Sapele
1500
Brazilian Maple
1500
Maple
1450
Royal Mahogany
1400
Caribbean Walnut
1400
Australian Cypress
1375
White Oak
1360
Ash
1320
Beech
1300
Red Oak
1290
Yellow Birch
1260
Caribbean Heart Pine
1240
Heart Pine
1225
Teak
1155
Eucalyptus
1125
Peruvian Walnut
1080
American/Black Walnut
1010
American Cherry

Wood Flooring Installation Tips
How To Install Wood Flooring
hardwood floor installer
Depending on construction & subfloor, wood flooring can be nailed, stapled, glued, or floated.
Your floor’s construction will determine your installation method. As a general rule, almost all solid wood floors require a nail or staple down install; whereas engineered flooring can typically be nailed, stapled, glued, or floated depending on your subfloor.

Unfinished solid hardwood flooring is installed over wood subfloors or is created with a floor joist system. Installation involves nailing or stapling. Most solid unfinished flooring is 3/4ths of an inch to one inch thick and 2.25 to five or seven inches wide. Smaller strip sizes are also available, and unfinished hardwood flooring can be 5/16ths to one-half of an inch thick and 1.25 inches wide. Unfinished solid hardwood is considered the highest-quality flooring product available, and installing thinner strips of this top-notch wood results in lower vertical floor height.

Able to be installed above, on, or below grade, unfinished engineered wood floors expand and contract less compared to solid hardwood when exposed to moisture and heat. In order to achieve this, engineered flooring manufacturers put together three to nine separate layers of hardwood, with the grain on each facing a different direction.

We ALWAYS RECOMMEND that you refer to your wood floor’s manufacturer to determine their approved method(s) of installation.

Whether you need to nail, staple, glue, or float The National Wood Flooring Association (NWFA) provides a detailed guide with instructions on how to install a subfloor, solid hardwood flooring, and engineered wood floors.