The secret to choosing a wood floor that's right for you

Are you considering purchasing a wood floor?
Do you have a wood floor and wonder why it scratches so easily?
Did you know there is a universal hardness rating scale for wood floors?

It’s called the Janka rating. (See below for a Janka rating scale) The Janka rating assigns a numeric value to wood species based on the Janka Hardness Test.
The test measures the force required to embed a .444” steel ball into a sample of wood half of its diameter.

The industry benchmark is Red Oak, which has a rating of 1290. The relative hardness of all other wood species are compared to this benchmark.

Red Oak -1290

Okay, what does that mean?

We all know the harder the wood, the more durable, more resistant to scratches, longer life, etc. So the question is, how hard is your floor? To know that you first have to determine the species.

Red oak makes up roughly 37% of all wood floors installed in the United States. Why? Red oak is a domestic product and, compared to nearly every other domestic, it is more common (cheaper) and has a higher Janka rating (1290).

A few examples of other domestic species with higher Janka ratings are:

White Oak -1360

Maple -1450

Hickory -1820

Each of these has a different look than Red Oak, which factors into its popularity along with, obviously, cost (all are less common compared to Red Oak).

A very common domestic hardwood seen in many older homes is Yellow Pine -690-870 (depending on what part of the tree the wood was taken from). Yellow pine is extremely soft. A dog’s nails will scratch grooves into Yellow Pine very easily.

Yellow Pine -690-870

An increasingly popular choice for wood flooring is bamboo, which is a grass, not a wood. Bamboo is very hard -1650 because of how it is manufactured. We have an entire blog post about bamboo manufacturing. I’ll put the link at the bottom. I’ve seen staples bend during the installation of strand woven bamboo flooring.

Bamboo -1650

Other popular imported high Janka rating species are:

Santos Mahogany -2200

Brazilian Cherry -2820

Brazilian Teak -3450

Hardness should play a large part when considering what type of wood floor you are going to purchase. Questions you should ask yourself:

• What kind of traffic will my floor get? (Kids, dogs, commercial etc.)
• Am I willing to live with scratches in the floor (sometimes they can add to the character)
• What can I afford?
• How long do I want my new floor to last?

Finally, the beauty of wood floors (and even bamboo in some instances) is they can be sanded and refinished giving your floor a completely new or different look. A quality wood floor should last as long as the house around it.

A very cool time-lapse video of a floor sanding and refinishing:

The Janka Rating scale

Learn more about how bamboo floors are made.

The secret to preventing your wood floors from failing

To prevent your wood floors from failing (coming apart, pushing together, cracking or worse), you must first understand them...and they're more complicated than you'd think (like some people I know).

Come winter, Fall, Summer, Spring, wood floors behave differently.  They also behave differently depending on where you live. Why?

Humidity.

Ever notice in the humid summer months your doors stick?  This is because wood swells when it is humid.  The same can be true for wood flooring. Both solid hardwoods and engineered hardwoods are susceptible.  

The inverse is also true. Low humidity causes wood to shrink.

Any floor, solid or engineered will expand or contract with changes in humidity.  The wider the flooring, the more expansion and contraction. This means any floor, solid or engineered may and often does experience seasonal gapping or cupping (see below for definitions of gapping and cupping). Seasonal gapping and minor seasonal cupping is normal.  When purchasing a solid or engineered wood floor, your salesperson should tell this to you so you aren't caught unaware and think your floor has a problem after it's installed.

The amount of seasonal gapping/cupping depends on many factors.  Species, thickness, wood grain orientation and width are the main factors.  

Can you avoid seasonal gapping/cupping?  No.  In theory, you could if you maintain a completely stable relative humidity throughout the areas with the wood floors.  In reality, this is impossible.  Regardless of how tightly sealed your windows are, how effective your dehumidifier is, the humidity levels in your home will change.

35% - 55% is the recommended relative humidity range for wood floors

Good news.  You can keep seasonal gapping/cupping to a minimum (and avoid ruining your floors) by keeping the relative humidity within the recommended range. 35% - 55% is the recommended range.  A good flooring company won't even install a wood floor without checking moisture levels in your home and confirming the humidity is within range.  (if they don't, insist they do) Once they're done with the install it is up to you to see that you provide your floor a nice, cozy environment.

How?

Purchase a hygrometer.  A good flooring company (like Bob Wagner's) will provide one when you purchase your floor.  This allows you to monitor humidity levels and confirm that your home is ready for the install.

 What happens if my home's humidity levels move out of the recommended range?

 Cupping, crowning, gapping, oh, my! (and buckling)

Gapping: low humidity causes the wood planks to shrink and move away from each other causing a gap between planks.

Gapping

Cupping: The edges of the floor planks are pulled up while the center remains lower.  This happens when the top of the floor looses moisture but the bottom doesn't follow.  It can also happen when the bottom of the planks absorb moisture from the subfloor and expand.  Minor cupping is a normal result of seasonal relative humidity levels.

Crowning: The center of the floor planks are higher than the edges.  This happens when the moisture on the top of the floor is higher than the bottom.

 Buckling: Extreme expansion of the floor planks.  Usually caused by a water leak or severe moisture conditions.

Buckling

What if the humidity levels creep toward the edges of the recommended range?

If your home starts to close in on the 35% range, turn on your humidifier.  Don't have one?  Buy one.  No doubt you've spent quite a bit of money on your floor.  If you don't want it ruined, invest in a humidifier.

If your home starts to close in on the 55% range, turn on your (you can probably tell where I'm going with this) dehumidifier.

Where you live will determine whether you are likely to need one or the other or both.  If you live in Houston, for example, chances are you'll never need a humidifier.  Live in Phoenix and you'll probably never need a dehumidifier.

For those of us who live in more seasonally affected areas, having one of each (or a whole house unit) is wise.

Typical seasonal impact on wood floors looks something like this:

Spring: low to moderate humidity levels, not much seasonal gapping in the flooring

Summer: moderate to high humidity levels, floor joints will swell and press against each other

Fall: low to moderate humidity levels, not much seasonal gapping in the flooring

Winter: moderate to low humidity levels, most seasonal gappinng occurs in the winter

Is there a 'best' season to install my hardwood floor?

Spring and fall, when the humidity levels tend to be the most 'average' for the year.

Just remember,

humidity is EVERYTHING when it comes to wood floors.