Hardwood Flooring


Solid Hardwood

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.

Types of Hardwood Cuts



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 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. For instance, it cannot be installed below grade. Neither can it be installed 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

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.

Engineered hardwood has several advantages over solid hardwood:

• It can usually be installed on all grades, including below grade

• It can be installed over radiant heat (with some limitations)

• 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 used over a radiant floor heating system. Generally speaking, the more plies in the plywood, the higher the price. A high-density fiberboard core is more dimensionally stable than a plywood core.

There are three different 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.

Wood Veneer Sawing Methods

The thickness of the veneer ranges from 0.6 mm to 6 mm. The thicker the veneer, the more expensive the flooring is, generally speaking. 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.

Cannot be sanded & refinished:

• Engineered wood floors with veneer thickness less than 2mm

• Handscraped engineered floors, regardless of veneer thickness

Can be sanded & refinished:

• Engineered wood floors with veneer thickness of 2mm or greater

Note: Sanding and refinishing an engineered wood floor with a veneer thickness of 2mm to 2.5mm 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.

Grades of Hardwood

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.

It is important to note that grading typically refers more to the look of the floor versus the quality of the floor. 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.

Common Grading Names

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 worm holes, no splits, no loose knotholes.

Shorts: 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.

Prefinished vs Site Finished

Prefinished boards are finished by the manufacturer, using several coats of finish with aluminum oxide, a surface coating which 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.

Surface Texture Types

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 different 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.

Installation Types

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 therefore can be installed over just about 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.

The Janka Hardness Scale

The Janka hardness test measures the resistance of a sample of wood to denting and wear. It measures the force required to embed a steel ball of diameter 11.28 millimetres (0.444 in) halfway into a sample of wood.

For hardwood flooring, the test requires a 2″ × 6″ sample with a thickness of at least 6–8mm. The Janka test is always carried out on wood from the trunk of the tree (known as the heartwood) and the standard sample is at 12{977bff95c21752fd93cd871a90668e4c2c7af99f8ecbf483fa46cb90a37db2d4} moisture content and clear of knots.

NOTE: Silver Maple ranks at 700 on the Janka Hardness Scale.