How to Protect Wood Floors from Moisture

You’ve just finished the installation of a beautiful oak floor. You step back and sigh in satisfaction. It’s complete.

You’re happy, and your customer is happy.

But only a few weeks later, your phone rings. It’s the same customer, complaining that the floor you just put in is turning upward from the edges, a problem called cupping.

The culprit? Moisture.

As someone who cares about your customers and the success of your work, you go inspect the issue and take care of fixing it. Thankfully, this was a small amount of cupping. But in some cases, you could even have to replace the flooring!

So what can you do to protect your work and your clients’ floors? How do you avoid these scenarios?

We’re here to look at some simple protection strategies you can use, as well as ways you can advise your customers in caring for their floors. We’ll cover:

• Why moisture control matters for wood flooring
• Pre- and post-installation steps for protecting wood floors

Why Moisture Control Matters for Wood Flooring

Moisture can lead to major issues with wood flooring. Wood naturally absorbs and releases moisture until it matches the moisture levels of its environment. And this equilibration process will continue if the environment changes.

As wood absorbs or releases moisture, it swells or shrinks accordingly. This can lead to warping and other kinds of damage, as mentioned earlier. The most common moisture issues with wood flooring include:

• Cupping
• Crowning
• Buckling

As a floor installer, you can avoid these kinds of issues, in part, by taking certain steps before and during installation. We also recommend advising your clients on how to care for their floors. Let’s look at more details next.

How to Protect Wood Floors from Moisture

A major part of protecting wood floors is being aware of the moisture content of the wood and working with that moisture. This includes the wood of the floor and the subfloor.

Of course, not all aspects of this care are within the control of the floor installer, but we’re here to look at what you can do:

1. Determine the Equilibrium Moisture Content (EMC) of the Wood

The equilibrium moisture content (EMC) is the moisture content a piece of wood will reach at a specific temperature and humidity level. Every location has its own EMC, and indoor environments tend to have a more consistent one.

In general, the ideal number for wood flooring in an indoor environment is 6–9%, though this number will vary depending on whether you’re in a dry climate like Utah or a humid climate like South Carolina.

Use an EMC chart or calculator to determine the EMC for the final location of the floor. Then, the goal is to get the floorboards to that number before installation. This will ensure they remain at a consistent moisture level once they’re in.

2. Prepare the Environment

Since temperature and humidity can fluctuate even within an indoor environment, check that the location of the new flooring is at service conditions before installing the floor.

Prepare the environment so that it has a consistent temperature and relative humidity and so that there isn’t excess moisture on the jobsite.¹ You may have to request the client to run their dehumidifier or HVAC system.

Typically, homes should be at a consistent number between 30 and 50% relative humidity and 60 and 80 degrees F.

The National Wood Flooring Association recommends:

“Verify that the room and building receiving new flooring is maintained at the expected in-use (e.g., normal living) conditions for temperature and humidity for a minimum of five days preceding installation to promote proper conditioning of the space (longer jobsite conditioning may be necessary due to tighter building envelopes). These same conditions should be maintained during and after installation.”²

3. Make Sure the Moisture Content of the Floorboards Matches the EMC

Use a wood moisture meter to check the moisture content of the floorboards. It’ll help you know whether the wood matches the EMC or not.

If not, it may need to acclimate in its final environment until it has reached that critical number.

We recommend using a pinless wood moisture meter, which has an electromagnetic sensor that scans the wood. This way you won’t damage your client’s floors with pinholes from a pin meter.

So, how many readings should you take?

The NWFA recommends checking 40 boards for every 1,000 square feet of flooring that you’re going to install. And as mentioned before, you should look for a reading around 6–9% MC, depending on the location.

If the wood has more or less moisture within it than its surrounding environment, open up the boxes of flooring and allow them to sit in the environment until they have reached the EMC.

4. Check the Moisture Content of the Subfloor

Not only is it important for the floorboards themselves to match the EMC. The subfloor, if wood, must also be close to that number. Use a wood moisture meter to check 20 boards for every 1,000 square feet.

The NWFA specifies that subfloor materials should be within 2–4% MC of the floor, specifically:³

• No more than 4% for solid strip flooring (less than 3 inches wide)
• No more than 2% for solid plank flooring (3 or more inches wide)

If the subfloor is concrete, use a relative humidity test or a concrete moisture meter to test the moisture levels and determine whether they match the floor covering manufacturer’s requirements.

5. Advise Customers on Wood Floor Maintenance

Since you can’t control what happens after you’ve finished an installation, the best thing you can do is give your customers some advice on caring for their floor.

One of the most critical steps they can take to prevent moisture damage to their wood floors is to keep their homes at a consistent temperature and relative humidity. Depending on their location, they may need to run dehumidifiers, air conditioning, or humidifiers to compensate for seasonal changes.

An environmental data logger or an in-floor data logger makes this even easier. In-floor data loggers, which are becoming more popular today, usually attach to the underside of a floor plank. From there, they monitor conditions of both the floor and subfloor in real time, sending alerts when either the temperature or humidity goes out of a set range.

As a floor installer, you could even consider including a wood floor data logger in your installation package. This way, you increase the likelihood of protecting your customers’ floors against harmful changes.

Aside from these bigger steps, also advise them with the following basic tips:

• Clean up spills immediately.
• Avoid the use of wet mops and opt for a cloth or dust mop instead.
• Perform routine checks of areas that are prone to leaks (sinks, water lines, etc.).
• Put down rugs and mats to catch water from shoes.
• Seal gaps around windows and doors to prevent moisture from coming in.

Start with a Wood Moisture Meter

Paying attention to moisture is the ticket to work well done, and the assurance that it’ll last. Taking these steps will allow you to say goodbye to frustrating scenarios of floor damage and customer complaints!

If you’d like to learn more about wood moisture meters and how they can help you have successful wood floor installations and protect your hard work, we’ve researched the best ones out there. Save yourself any guesswork by taking a look at our top reviews.