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  • Acclimation: How and Why to Acclimate your Trinity Bamboo Floor
  • Post author
    Tom Goodham

Acclimation: How and Why to Acclimate your Trinity Bamboo Floor

Acclimation: How and Why to Acclimate your Trinity Bamboo Floor

A question that all folks should be asking is “do I need to acclimate my new floor before I install it, and if so, for how long?”  What makes this topic a bit difficult is the number of variables involved.  Let’s get a few terms out of the way so that we are all speaking the same language.

Relative Humidity:  Roughly speaking, relative humidity (RH) is the amount of water vapor present in air as a percentage of how much water vapor the air can potentially hold at a given temperature.  Warmer air, for example, can hold more moisture vapor than colder air.  So, air with 70% RH at 80 degrees Fahrenheit will have more actual moisture in it than air at 70% RH at 20 degrees Fahrenheit (even though the reading at both temperatures would be 70% RH).  Technical explanations aside, if your house has a high relative humidity it has more moisture in the air than your house does when it has a low relative humidity.  Muggy versus dry air.  Hawaii versus Mojave Desert. 

Moisture Content:  The moisture content of the wood/bamboo in your home is determined by two factors: Your home’s temperature and your home’s relative humidity.  If you increase the temperature and relative humidity level in your home, the moisture content of all the wood/bamboo in your home will rise and the wood/bamboo will expand.  If you decrease the temperature and relative humidity level in your home, the moisture content of all the wood/bamboo in your home will decrease and the wood/bamboo will shrink. 

Acclimation: Bamboo and wood flooring interact with the surrounding environment (subfloor, air, dogs, etc.) and take on moisture or give off moisture until a state of equilibrium is reached with the environment. Acclimation is the art (and the science) of preparing your new floor for installation by allowing it to reach a moisture content level in equilibrium with the average air temperature and relative humidity levels inside your home.  Your new floor should be acclimated prior to installation.

The following chart shows the approximate moisture content of wood/bamboo when it has reached equilibrium with (is acclimated to) air at a specific temperature and relative humidity level:

To put the above chart into practical terms, if you remove a flooring plank from a new box of flooring and it has a moisture content of 8.5% at 70 degrees, it will not expand or contract when placed into a 70-degree house which has a relative humidity content of 45% (known as 45% RH). See the purple areas in the above chart.  To put it another way, a plank at 8.5% moisture content is in equilibrium with air at a temperature of 70 degree at 45% RH.

What happens if we install the same plank into a house with an interior relative humidity of 60% RH at 70 degrees?  The moisture content of the plank will rise until it reaches equilibrium with the environment.  This means that your plank will swell until its moisture content reaches 11%.  If you install this same plank into a house with an interior relative humidity of 30% RH at 70 degrees, your plank will shrink until its moisture content reaches 6.2%.  This swelling and shrinking of wood/bamboo is totally normal and happens around us all the time.  The key here is that we want most of the swelling or shrinking to occur before you install your new floor to avoid problems such as buckling (from excessive swelling) or gapping (from excessive shrinking).  How do we avoid these problems?  Acclimate prior to installation.

Your mission is to acclimate your flooring at, and install it into, a temperature and relative humidity controlled environment representing the average environment you expect to be present in your home year-round.  Again, we don’t want to acclimate and install into an abnormally cold and dry house nor do we want to acclimate and install into an abnormally humid and hot house.  We want to acclimate and install your floor into the average environment (temperature and relative humidity) your house will be maintained at year-round.  How does a person know the average temperature and relative humidity levels inside their house?  One option is to keep records of your house’s average temperature and relative humidity levels.  Thankfully, this is easy (and fun!).  Purchase a low-cost digital Thermometer and Hygrometer (around $15.00) and then take notes.  If you don’t have a year to monitor readings in your house see if any of your neighbors have a weather station and see what their indoor environment is like over the course of a year.  A call to your local HVAC specialist might provide you with some excellent insight as well.  Bear in mind that your house (with your heating and cooling system) will assuredly be a bit different than your neighbors’ house.

If you can’t get any local data, take a look at the following chart created by The USDA Forest Products Laboratory.  It lists the average moisture content of wood in interior environments across all the states in North America. 

United States Department of Agriculture, Forest Products Laboratory FPL–GTR–190

How would you use the above chart?  Example: You live in North Dakota.  The chart shows an average moisture content for wood at 8%.  You keep your house at 70 degrees year-round.  You should, ideally, acclimate your floor at a relative humidity level between 40% and 45%.

How to Acclimate your new Floor:

Once all “wet-work” has been complete (plaster, painting, etc.) make sure your Heating/Cooling system is operating and set to the average temperature and relative humidity your house will be maintained at year-round.  Next, remove all the planks from the boxes and sticker stack them off the floor so that the planks are adequately exposed to the air in the installation environment.

Sticker Stacking in real-life brought to you by Robert Rosser and his excellent team in Florida: Note that every layer is separated by cardboard (cut from the box) to allow for air-flow between planks.

How long will acclimation take? A good rule of thumb is to acclimate your Strand Bamboo floor (engineered or solid) for about 7 days per every percentage point of projected change in moisture content.  Because Trinity Bamboo flooring will be delivered to you having an average moisture content of 8.5%, I would suggest the following acclimation schedule:

  • Acclimate for a minimum of 72 hours (for perfect environments) or 7 days per desired 1 point change in moisture content:
    • Example: If your house has an interior average relative humidity level of 35% at 70 degrees you will need to acclimate your floor to a target moisture content of 6.9% prior to installation. To do this, you will need to acclimate your flooring for about 11 days.  Here’s the math:
      • 5% - 6.9% = 1.6 points change
      • Multiply 1.6 x 7 days = 11.2 days acclimation
    • If you live in coastal Florida where your house has an interior average relative humidity level of 65% at 70 degrees, you will need to reach a target moisture content of 12% prior to installation. To achieve this, acclimate for about 25 days.  Here’s the math:
      • 12% - 8.5% = 3.5 points change
      • Multiply 3.5 x 7 days = 24.5 days acclimation

Use a moisture meter to confirm your flooring is acclimated to the environment.  How will you know when acclimation is complete?  The moisture content of your floor will no longer change (or will change very slowly).  When in doubt, more acclimation is better, as long as you are acclimating your flooring to the average annual relative humidity and temperature range for your house.  Again, never acclimate to an extreme environment.  Always acclimate to your household average relative humidity and temperature.

How to measure moisture content (MC):  In truth, it is difficult to know the exact moisture content of any natural flooring, bamboo or wood.  Why?  Because moisture meters (by necessity) make a lot of assumptions about the density and composition of the material they are measuring.  If the density of the material being tested is different than the standard, guess what?  It will measure a bit high or a bit low.  Just like any other natural material, all Strand Bamboo flooring has varying degrees of density from batch to batch and even from plank to plank.  Well then, how then do you know if your flooring is acclimated to an environment?  It’s moisture content will stop changing.  This is where the moisture meter really comes into play.  Rather than test flooring planks to obtain an exact moisture content, test planks to understand when their moisture content is no longer changing.  The good news is that almost any moisture meter can do this.

As always, every situation is a bit different.  This is why it is sometimes important to hire a professional to perform your flooring installation.  Don’t cut corners and don’t hire someone who will.  If you have any questions give us a call at 1-888-248-6538.  We’ll gladly spend as much time working with you as you need.  Free technical support from kind people – we’re Trinity Bamboo.

  • Post author
    Tom Goodham

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