Types and Grades of Hardwood Flooring

A crucial decision in the hardwood buying process before you begin is deciding among the types and grades of hardwood to use. As there are many different options available, making the right choice relies on a variety of factors. When trying to decide on details like the grade of hardwood to use, it is important to consider the construction type, the species, the installation type, whether the wood is prefinished or unfinished, and basic style and color options to suit décor needs.

The standard thickness for solid hardwood is 3/4″. For thin profile solid hardwood, 5/16″ is the standard. The planks are sawn in one of three ways, which affects the stability and the price of the hardwood.

• Flat or Plain Sawn: the most common cut. It has more variations than the others.
• Quarter Sawn: cuts a log into quarters before it cuts the strips of wood to make hardwood flooring boards.
• Rift Sawn: cuts a log at a different angle than quarter sawn before it cuts the wood into hardwood flooring boards. Though it is more expensive than the other methods, it is also more stable, providing higher quality flooring.

Solid hardwood floor planks are made with a tongue and groove edge locking method which makes it easy to join the planks together and make a strong joint. One side of the board has a tongue and the other has a groove. The tongue interlocks with the groove to fit the boards together.

One of the advantages of solid construction is that most 3/4″ thick solid wood floors have about 1/4″ or 6 mm (about 0.24 in) of wood above the tongue and groove, meaning they can be sanded and refinished many times. If properly cared for, a solid hardwood floor can last for generations.

There are some potential disadvantages of solid hardwood. It cannot be installed below grade or over radiant heat. Most experts recommend not installing it over a concrete subfloor. And finally, it tends to be pricier than engineered wood flooring.

Engineered hardwood is made by gluing a real hardwood veneer to a core board made of either plywood or high-density fiberboard. Because of this construction method, engineered hardwood is more dimensionally stable than solid hardwood. In other words, it will not contract or expand as much due to changes in humidity or temperature.

As a solid hardwood floor alternative, engineered hardwood has several advantages over solid hardwood:

• It is generally less expensive than solid hardwood
• It can usually be installed on all grades, including below grade
• It can be installed over radiant heat
• It can be installed over a concrete subfloor
• It can be floated

The number of plies used to create the plywood core may vary anywhere from 2 to 10, and while a 3 ply board is not going to be as stable as, say, a 5 ply board would be, this difference is not enough to be a deciding factor unless the flooring is going to be used over a radiant floor heating system. Generally, the more plywood piles, the higher the price. A high-density fiberboard core is more dimensionally stable than a plywood core.

There are three diverse ways of cutting the veneer for the engineered flooring that, along with thickness, has an impact on price. The three methods of cutting the veneer include:

• · Dry solid-sawn: involves letting the wood dry out slowly with a low humidity level to keep moisture from inside the wood cells intact, reducing the risk of cupping. It is the most expensive type of engineered flooring but looks and acts more like a solid.
• · Rotary- peel:  involves boiling the log for a certain amount of time at a certain temperature to prepare the wood. After the wood has been prepared, it is scraped from the log with a blade working from the outside in and then pressed flat. Rotary-peel typically has a plywood-like grain and can have issues with cupping and warping to try to revert to its original shape.
• · Sliced- peel: involves boiling the log for a certain amount of time at a certain temperature to prepare the wood. After the wood has been prepared, it is sliced from the end and then pressed to create a veneer.

The thickness of the veneer ranges from 0.6 mm (about 0.02 in) to 6 mm (about 0.24 in). The thicker the veneer, the more expensive the flooring is.

For people who are planning to refinish the flooring at some point, it is important to consider the thickness because, unlike a solid hardwood floor, the engineered type can only be sanded and refinished so many times. The thicker the veneer, the more times it can be sanded and refinished, however, it is still limited. Once installed, removing a vent to inspect the flooring from the side can provide an idea of the remaining thickness on the veneer.

• Engineered wood floors with veneer thickness less than 2mm (about 0.08 in)
• Handscraped engineered floors, regardless of veneer thickness

• Engineered wood floors with veneer thickness of 2mm (about 0.08 in) or greater

Note: Sanding and refinishing an engineered wood floor with a veneer thickness of 2mm (about 0.08 in) to 2.5mm (about 0.1 in) is best left to a professional.

Engineered floor planks are made with either a traditional tongue and groove edge locking method or with a glueless click-lock edge method that requires no glue and allows the pieces to snap together to create a snug fit. This is the easiest do-it-yourself installation method.

Acrylic impregnated floors have acrylic compounds injected directly into the wood, resulting in a stronger, harder, more durable wood. While these are more commonly seen in commercial settings, this kind of floor may do well in a busy home with lots of traffic. These floors can handle more moisture than the standard hardwood floor as well.

While not a different construction type, these wood floors are unique in that they have been made from reclaimed wood. The wood may have been reclaimed from sunken boats, from logs salvaged from lakes and rivers or from old buildings and reprocessed. This type of flooring is good for those who want sustainable flooring and can be found either of solid or engineered construction type.

This is an interesting area for shoppers, retailers, and manufacturers. While the National Wood Flooring Association, or NWFA, has established a grading system, it only applies to certain domestic species. There is no universal system for international grades of hardwood.

Note that grading typically refers more to the floor's look versus the floor's quality. For example, an antique-grade floor is just as structurally sound as a floor graded as select and better. The antique floor will have more of a rustic look to it with more character marks.

Many manufacturers create their own grades of hardwood, which apply more to the look of the wood than the strength, stability, durability, and quality of the flooring. When it comes to engineered hardwood, most sellers do not make grading information available.

When shopping for hardwood, there may be several different grade names present.

The most common grades of hardwood for prefinished products are:

• Clear Grade: This is the best of the grades of hardwood flooring because there are few color variations, board lengths are not widely varied, and there are little to no visible knots or pinholes.
• Select and Better: This grade is slightly lower than the clear, still presenting uniform color and little to no knots and pinholes.
• #1 Common: This grade presents with more color variation, shorter board length with greater length variation, and an increased chance of visible knots and pinholes.
• #2 Common: Boards show natural character, with darker and lighter boards, shorter board length, with an increase in visible knots and pinholes.
• Cabin Grade – Cabin grade is for those who are looking for a rough-hewn look in hardwood flooring; allowed checking, unfilled knot holes and wormholes, no splits, no loose knotholes.
• Shorts: This has the most visible character with many knots, pinholes, and color variations present.
• For unfinished hardwood products, these are the commonly seen grades of hardwood:
• Clear Grade: As above, this is the best grade of hardwood flooring. Few color variations, similar board lengths, and little to no visible knots or pinholes.
• Select and Better: This grade is slightly lower than the clear, with uniform color and little to no pinholes and knots.
• Country or Exclusive Grades: This grade presents with more color variation, shorter board length with greater length variation, and an increased chance of visible knots and pinholes.
• Traditional, Antique, Character Grades: Boards show natural character, with darker and lighter boards, shorter board length, with an increase in visible knots and pinholes.
• Tavern or Cabin Grade: This has the most visible character with many knots, pinholes, and color variations present.

It is worth noting that some sellers combine grades of hardwood. For example, a floor may be sold as #1 common and better, meaning it is a combination of #1 common, select and better and clear grades. In this case, you will want to find out from the seller the proportion of each grade.

Prefinished boards are finished by the manufacturer, using several coats of finish with aluminum oxide, a surface coating that is the second hardest substance in the world, next to diamond. Special equipment dries the finish almost instantly, creating a durable surface for people to walk on. These are more expensive than unfinished floors but can be installed in the home without having to worry about sanding and finishing.

Site finished flooring is unfinished hardwood installed on the site and then finished. These boards cannot use aluminum oxide, because by the time the finish dries (several hours in some cases) the aluminum oxide particles will sink to the bottom, therefore not providing a hardened surface for people to walk on. There are several other durable finishes and sealers to choose from.

There are a few different surface textures available to help buyers get the look they want. Each one of the texture options below offers a unique style to be considered for decor purposes.

• Smooth: This refers to traditional milled boards.
• Hand Scraped: This refers to boards that are distressed by hand.
• Distressed: This refers to boards that are distressed by machine.
• Antique: This refers to the boards with the appearance of extreme age.
• Wire brushed: The wire brush texture consists of a wire brush run over wood flooring, creating a rough, hard surface . The wire brush gets rid of the soft wood on the surface, making the floor more durable, less slippery, and easier to maintain . This surface also hides scratches and makes the wood surface look old, which some people like.

There are many different species available to use for hardwood flooring. Choosing the right species is important as each species has distinctive characteristics, colors, and grain patterns. Each kind of wood has a hardness rating on the Janka Hardness Scale which can show how well the floor may hold up over the years; however, any floor may show early signs of wear and tear if not properly maintained .

The following species are some of the more popular domestically grown and processed: White Ash, Beech, Birch, Black Cherry (aka American Cherry), Hickory-Pecan, Sugar Maple, Mesquite, Red Oak, White Oak, Pine, and American Black Walnut, Sugar Maple Hardwood.

The following species are some of the more popular exotics, imported from other countries: Bamboo , Brazilian Cherry, Bubinga, Cork, Cumaru, Spotted Gum, Sydney Blue Gum, Iroko, Jarrah, Mahogany, Brazilian Maple, Merbau, Tasmanian Oak, Padauk, Purpleheart, Brazilian Teak, Thai Burmese Teak, Brazilian Walnut, and Wenge.

You can divide hardwood into installation categories, and you might want to select your hardwood this way, ensuring you pick a floor with the kind of installation you prefer:

• Nail/Staple down: Nail down uses nails to attach the wood to the subflooring, and staple down uses staples to attach the wood. Staple down is simpler than nail down. Neither nail nor staple down is suggested for novice installers. Solid hardwood is often installed using this method.
• Glue down: If the flooring is an engineered hardwood, it can be glued to the subflooring with a strong adhesive. This method is rarely used on solid hardwood floors, except for some thin profile solids.
• Float: Available in the following two options, made for an easier do-it-yourself installation. These floors are not attached to the subfloor and can be installed over almost any surface. Usually, a moisture barrier and/or underpad is placed between the subfloor and the engineered wood floor.
• Glue-Seam: These floors use an adhesive to glue the pieces together.
• Glueless-Click: These floors snap together and require no glue.

There are many other design options that need to be considered when choosing the best hardwood flooring for your needs, including: color, gloss level, finish, edge detail, width and length.