How to Prevent Moisture Under Hardwood Floors

You’ve invested in quality wood flooring, so you’d want to keep it in good condition, right? One way to do this is to take measures to prevent moisture under hardwood. Thankfully, this isn’t rocket science—as long as you follow the correct installation and care procedures, you should be a-OK. Learn how moisture affects wood and the techniques for how to install wood flooring on concrete—a surface prone to moisture. You’ll also get tips for what is the best moisture barrier for hardwood floors and other installation and care advice to help ensure your hardwood stays in peak condition for years to come.

 

The Properties of Wood

Wood’s enduring beauty and character have stood the test of time—wood has been a natural and sustainable flooring material for centuries. When you bring wood into your home, you’ll bring its natural qualities right along with it, from its graining and texture to its ruggedness and longevity.

 

Wood is hygroscopic, a fancy word that means it can take in moisture from its surroundings. Because of this fact, it’s important to take certain measures to mitigate environmental moisture so your flooring can perform at its best. This is also true for engineered hardwood, which is a real wood product with a top layer of solid hardwood.

 

How Do You Reduce Moisture in Hardwood Floors?

When installing hardwood floors, consider any moisture that may come from underneath the boards and the air in your home. However, keep in mind that seasonal expansion and contraction are perfectly normal for wood flooring and shouldn’t be a concern. What you want to mitigate are high levels of moisture that can dramatically affect your flooring and its performance.

 

What measures can you take?

 

Choose the Right Wood Flooring

First, consider where you’ll be installing your flooring. Solid hardwood can go in rooms at and above ground level, while engineered hardwood can be installed on any level of the home, including in basements. You can install engineered and solid hardwood over concrete if certain mitigation measures are taken.

 

Concerning the natural seasonal expansion and contraction of wood flooring, choose narrower boards if you want to experience less movement. You could also select engineered hardwood, a more dimensionally stable product.

 

And last but not least, for extra defense against moisture—including spills and splashes—choose our AquaSeal line of engineered hardwood.

 

Acclimate and Test for Moisture

Once you’ve chosen your hardwood, it’s time to bring it into your home. But don’t install it right away! Follow your product’s Warranty, Installation, and Care (WIC) guide for specific instructions on how to acclimate your boards. This will help ensure the flooring is adjusted to the relative humidity and temperature in the room where it will be installed, which helps reduce future movement.

 

After acclimation, test individual boards with a moisture meter, which you can find at LL Flooring among our wide selection of tools and materials. If you’re wondering what is an acceptable moisture reading in hardwood floorboards, check your WIC guide.

 

 

Additionally, check the moisture content levels on your subfloor—whether wood or concrete—and address any moisture problems in the home if levels are high. You can find moisture testing kits specifically for concrete.

 

Install a Moisture Mitigation Barrier

Subfloor prep is important for floor performance in many ways—not the least of which is to mitigate moisture. So, do you need a moisture barrier under hardwood flooring? Exact mitigation measures will differ depending on the type of subfloor, flooring product, and installation method.

 

Since concrete slab is known to harbor moisture, a concrete subfloor will require the strongest moisture mitigation measures. When installing click-lock engineered hardwood over a concrete slab, use a 6-mil polyurethane film over the concrete before you install your underlayment padding and flooring. You could also use an underlayment padding that has moisture mitigation properties included.

 

Another installation option is to glue your floor down. If you’re going that route, use an adhesive that contains moisture vapor control.

 

If you’re installing plywood over the concrete to nail down your floor, put a 6-mil ply moisture barrier or a roll-on/trowel-on moisture barrier coating between the concrete and plywood before installing your engineered hardwood.

 

With solid hardwood, since you’ll be dealing with at-grade or above-grade installation, you’ll likely have a plywood subfloor. Do you, therefore, need a moisture barrier under wood floors, even if you’re installing over plywood? Although a moisture barrier is not required, we highly recommend using one. And whether installing solid or engineered hardwood, an additional underlayment will increase sound insulation and comfort underfoot.

 

For adhesives, coatings, and a variety of subfloor prep and underlayment options, look no further than LL Flooring.

 

Install Your Flooring Properly

Your WIC guide will have step-by-step instructions for installing your hardwood flooring using the methods appropriate for your specific product. Keep in mind that glue-down and nail-with-glue assist installation can help limit some of the seasonal movement associated with changes in humidity and temperature.

 

Don’t forget the trims and moldings that complete the look of your flooring—such as baseboard and quarter round, thresholds, and stair noses. Save time by buying them together with your flooring, but make sure the items are correctly coordinated. It also doesn’t hurt to acclimate these items together with your flooring.

 

Keeping Moisture at Bay

To keep your new hardwood flooring in its best condition, keep your home within the range of temperature and humidity levels recommended by the manufacturer. Occasional splashes and spills shouldn't ruin your floor but try to clean them up as soon as possible. This is especially true for solid hardwood.

 

Browse our Flooring 101 for more installation tips, as well as flooring care and maintenance guides to help keep your hardwood floors looking new for years to come.

 

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