How Hard are Hardwood Floors, Really?

Just  the other day I was at a home inspection (representing the sellers) and the buyer’s home inspector was commenting on the Brazilian Cherry floors in the Study, telling the buyers that “this wood is very soft, so you’ll want to be very careful when you walk on it.”

Having grown up in the household of a high school shop teacher, I’ve had a great education in woodworking and made lots of projects with my Dad.  Over the years I’ve worked with Brazilian Cherry and for a fact I know it is a very, very hard material.  It takes forever to sand and holes for fasteners have to be pre-drilled very accurately and sized correctly. But I kept that knowledge to myself and decided to share it with you instead.

Many woods are used for flooring and although today’s design trends and color schemes often drive the choice of materials, over time the most popular woods for this area of the country, are: Brazilian Cherry, Mahogany, Pecan, Maple, White Oak, Red Oak, Walnut, Teak, Pine, and Fir. Of these, Red Oak is the most commonly used (it’s considered the most color-neutral and affordable of the woods) and thus it is considered the standard or benchmark in wood hardness.

If you Google hardwood hardness you will inevitably encounter the Janka Hardness Scale. It is the industry standard for judging the ability of woods to withstand the beating that wood takes from normal wear and tear: denting, gouging, pet scratches, heavy furniture, etc. Janka measures the amount of force in lbs-force that it takes to push a half-inch diameter (okay it’s really .444 inch) steel ball half of its diameter down into the wood. While this gives a general sense of the wood’s hardness, there are many factors that also contribute to a wood floor’s hardness and durability, including how it is cut from the log and how it is finished.

How the tree is cut has an effect on its hardness and suitability as a floor covering. Hardwood flooring is produced by milling wood from trees. There are three basic ways to cut a tree into lumber, called “plainsawn”, “quartersawn” and “riftsawn”.

“Plainsawn” wood is just that, the log is sliced lengthwise from one side to the other in a series of parallel cuts, sort of as you’d cut a block of cheese. This gives the best yield from the tree but for flooring it tends to result in a very inconsistent grain pattern and tends to expand and contract in unpredictable ways. Wide-pine floors (found in many Antiques and Antique Reproduction homes) are the typical example of “plainsawn” wood that most of us will encounter.

“Quartersawn” wood is the most common way that flooring material is made. In this method, imagine that the log is cut down the middle, then both halves are cut down the middle, and the boards are then cut from the “quarters” with the point facing straight down (a series of parallel cuts starting perpendicular to the centerpoint of the tree). This gives consistency to the grain of the boards (as consistent as any natural material can be) and a predictable stability that makes it perfect for flooring. For the purposes of this blog, I am using hardness factors derived from “quartersawn” wood.

“Riftsawn” wood is the absolutely ideal material for consistency of grain and stability but is very hard to find because it is so expensive to manufacture. In this method, the log is cut into a series of wedges that are perpendicular to the rings of the tree. The wedges are then sawn into boards and the excess material becomes waste. Because of the low yield per tree the cost per board foot is very high and you will probably never see “riftsawn” flooring unless touring a mansion or a castle. By the way, there are a couple of specialty sawmills in the Sudbury area that will produce “riftsawn” boards for you, but hold onto your wallet.

As mentioned earlier, the finish also has an effect on the hardness. I am not qualified to comment on what finish is harder or better (best to ask a flooring expert) but I can tell you that the typical finish penetrates into the top ¼” of the wood, at most, so logic would have it that finished versus unfinished wood would be harder but much beyond that I can’t really say.

So how hard is my hardwood floor?

Below is a list from softest to hardest:

FIR
  • Latin: Abies sp
  • Other Common Names: White Fir, Balsam Fir, Fraser Fir
  • Janka Hardness: 400

WHITE PINE

  • Latin: Pinus alba
  • Other Common Names: White Pine, Eastern White Pine
  • Janka Hardness: 420
  • Hardness Compared to Fir: 1.05 times harder

SHORTLEAF PINE

  • Latin: Pinus echinata
  • Other Common Names: Southern Yellow Pine, Shortstraw Pine
  • Janka Hardness: 690
  • Hardness Compared to Fir: 1.725 times harder

AMERICAN CHERRY

  • Latin: Prunus serotina
  • Other Common Names: Black Cherry, Cherry, American Cherry
  • Janka Hardness: 950
  • Hardness Compared to Fir: 2.375 times harder

TEAK

  • Latin: Tectona grandis
  • Other Common Names: Plantation Teak, Burmese Teak
  • Janka Hardness: 1000
  • Hardness Compared to Fir: 2.5 times harder

WALNUT

  • Latin: Juglans nigra
  • Other Common Names: Black Walnut, Eastern Black Walnut
  • Janka Hardness: 1010
  • Hardness Compared to Fir: 2.525 times harder

HEART PINE

  • Latin: Pinus palustris
  • Other Common Names: Long Leaf Pine,
  • Also Commonly from: the Center or ‘Heart” of Yellow pine
  • Other Notes: mostly from recycled or underwater harvested, swamp trees
  • Janka Hardness: 1225
  • Hardness Compared to Fir: 3.0625 times harder

RED OAK

  • Latin: Quercus rubra
  • Other Common Names: Northern Red Oak
  • Janka Hardness: 1290
  • Hardness Compared to Fir: 3.225 times harder

WHITE OAK

  • Latin: Quercus alba
  • Other Common Names: Old Oak
  • Janka Hardness: 1360
  • Hardness Compared to Fir: 3.4 times harder

MAPLE

  • Latin: Acer saccharum
  • Other Common Names: Rock Maple, Hard Maple, Hard Rock Maple, Sugar Maple
  • Janka Hardness: 1450
  • Hardness Compared to Fir: 3.625 times harder

PECAN

  • Latin: Carya illinoinensis
  • Other Common Names: Hickory, Satinwood
  • Janka Hardness: 1820
  • Hardness Compared to Fir: 4.55 times harder

 

MAHOGANY

  • Latin: Swietenia mahagoni or Swietenia macrophylla
  • Other Common Names: West Indies Mahogany, Honduras Mahogany, Genuine Mahogany
  • Janka Hardness: 2200
  • Hardness Compared to Fir: 5.5 times harder

BRAZILIAN CHERRY

  • Latin: Hymenaea courbaril
  • Other Common Names: Brazilian Copal, South American Locust,  South American Cherry, Jatobá or Guapinol
  • Janka Hardness: 2350
  • Hardness Compared to Fir: 5.875 times har