So, how dry was it this winter?

I own a Nest thermostat. You know, one of those fancy Wi-Fi connected “smart” thermostats that learn your habits and adjust the temperature in the home automatically to save energy. I confess, it was more the gadget lover in me than the nascent environmentalist that wanted one, and I justified the purchase in the hopes it would save my family some money – and if I contributed to saving the environment, then so much the better.

One useful thing that I do get with a thermostat like this is a monthly report e-mailed to me on my home energy use for the previous month. Curious? Well, in Kansas City we still have the furnaces running for the most part. In February, it ran for 169 hours! March was a much better 75 total hours, saving me 94 hours worth of natural gas. Certainly the milder weather is to thank for the lower energy bill, but the thermostat is smart enough to know when nobody is home and will turn the target temperature way down until someone comes back. This and other features have undoubtedly helped us save.

However, the thing that caught my eye in the report this month was an “Interesting Fact” from Nest:

“Wonder how humid it was this winter? The average indoor relative humidity for Nest owners in your state was 26.5%. And across the country, the most common indoor relative humidity was 33.2%. Most people are comfortable when the humidity in their home is between 30% and 50%. You can check your current humidity in the Nest app or on your Nest Thermostat.”

Average indoor relative humidity.
Average indoor relative humidity across the U.S. for February 2015. (Nest)

How this relates to wood flooring

This stuck out to me because of how important indoor relative humidity and temperature is for wood flooring. For many of the prefinished engineered and solid wood floors that we sell, either we or the manufacturer recommend that the environment be kept between 35-55% relative humidity. This is important because wood is hygroscopic and seeks to be in equilibrium with the environment it is in. Practically, this means that wood flooring will absorb moisture when there is an excess of it in the air surrounding it. Wood flooring will also give up moisture, or dry out, when the air surrounding it is dry. Whenever wood takes on or gives up moisture it changes its physical form. This could result in the wood expanding, contracting, checking, cupping or splitting – none of which are desirable for flooring!

The map above illustrates the average indoor relative humidity levels for Nest thermostat owners in the month of February. While this certainly doesn’t apply to every home, it is clear that many homes struggled to maintain that ideal 35-55% RH level that is recommended for most wood flooring. I know for a fact that my house in Missouri got really, really dry this winter. I recall one day when my thermostat was showing a bone dry 13% relative humidity level. The gaps in my beautiful 2-¼” Red Oak floor from Hardwoods of Missouri were quite noticeable, and everything else made of wood in the house squeaked. It was a pretty cold winter, and my 60-year-old house felt it.

What you can do

This points to the need for some “help” in adding humidity when the weather gets really dry. Whole home humidifiers are a wise investment for homes in states that struggle to maintain appropriate RH levels if it’s important to you to avoid the symptoms of wood flooring getting too dry. Those of us in old drafty homes may be used to the seasonal gapping that occurs in our flooring. But for a new homeowner that just installed a beautiful new wood floor the symptoms can be jarring. And for some engineered wood floors, the damage done by excessive drying can be destructive to the floor and delamination or severe checking may occur. Board replacements are really the only option for this type of damage and none of it would typically be covered by manufacturer’s warranties because the flooring has clearly been exposed too long to very dry conditions outside the recommended range of 35-55% RH.

Whether you have a smart thermostat or not, having a hygrometer in your house to measure RH levels is a good idea and will help you evaluate whether or not you should consider installing a whole home humidifier to protect your investment in hardwood flooring.

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