How To Fix Wood Floor Cupping (7 Easy Steps)

How To Fix Wood Floor Cupping (7 Easy Steps)

Do you have wood floor cupping in your home? Have you been looking for an answer? If so, don’t panic!

Cupping is a common issue with wood floors. Wood flooring is susceptible to expansion and contraction due to changes in humidity. Too much moisture causes the wood to expand, pushing the boards together until the centers bow downward, forming individual troughs or cups.

This is less common in climate-controlled spaces. If water is spilled and left on wood flooring for too long, the hardwood soon cups. Ensure the subfloor and the wood are completely dry before attempting to repair the cupped flooring.

Fortunately, it’s relatively easy to fix, although it can sometimes be labor-intensive.

Here’s a breakdown of how to fix wood floor cupping:

Common Causes of Wood Floor Cupping

Hardwood flooring is available in two distinct varieties: solid wood and engineered wood flooring. Cupping can occur in both, although it is more likely to happen in solid hardwood floors.

Before beginning, it’s important to understand the most common causes of wood floor cupping. These include:

High Humidity

If you live in a humid climate, your wood flooring is more likely to experience cupping. Overly humid environments can cause wood to swell and distort. This is possible even if the flooring has been adequately sealed and protected.

In addition to damaging the floors, cupping can make them more difficult to clean correctly and cause trip risks.

Improper Installation

Improper installation is another common cause of hardwood floor cupping. If the hardwood planks weren’t installed correctly, there could be an uneven moisture distribution on the floor, causing them to cup as they expand and contract.

In addition, if the subfloor is not level or properly prepared, it can also lead to cupping. In order to avoid this problem, it is important to work with an experienced flooring professional who can ensure that your floors are installed correctly.

Leaks or Flooding

Leaks or flooding can also cause wood floor cupping. When water seeps beneath the flooring, the boards can swell and buckle. As the wood takes in water, it will eventually bend into a cup shape. Sometimes the damage is so bad that you must start from scratch and install brand-new flooring.

Cupping can also occur if the seal around the edges of bathrooms, sinks, and other fixtures have become compromised, and water can seep underneath the flooring.

Water Damage

Another common cause of wood floor cupping is water damage. Hardwood floors can swell and buckle if water gets underneath the boards and sits there for a long time. This can lead to a warped wood floor that is no longer level.

If you have water damage on your wood floors, it is important to have the damage repaired as soon as possible. Floors can be severely damaged by water damage and could become a breeding ground for mold if immediate action is not taken.


Small spills can also cause wood floor cupping. If a spill is left to sit on the floor’s surface, it can seep into the cracks between boards and cause them to expand. As they continue to absorb moisture, they will eventually cup.

Excess Subfloor Moisture

Cupping is often caused by excess moisture in the subfloor, which can come from a variety of sources. The subfloor is the layer of plywood or OSB that sits beneath the finished flooring and is designed to provide a stable foundation. However, if it becomes wet, it can cause the boards of the finished flooring to warp and cup.

For example, elevated humidity levels can lead to cupping in homes with crawl space. Excessive moisture can come from plumbing leaks or condensation from appliances such as refrigerators in homes without crawl space.

If left unaddressed, cupping can cause long-term damage to your floors. Not only will the boards become more susceptible to cracking and breaking, but the cupping will also become more pronounced over time.

How To Fix Wood Floor Cupping

There are several steps to fixing cupped hardwood flooring.

① Check For Moisture Issue

Ensure any leaks and other potential causes of excess moisture have been fixed before beginning the repair process. Use a moisture meter specifically designed for wood floors. These meters are sensitive enough to pick up on subtle changes in moisture content, which is important when trying to avoid damage to your floors.

Second, take readings at various points throughout the room, as moisture levels can vary depending on location. Finally, verifying the recommended moisture level with the manufacturer is important.

② Use a Dehumidifier

If the cause of cupping is related to seasonal fluctuations at various times of the year, this approach can be extremely useful. A dehumidifier can assist in alleviating the situation by removing excess moisture from the environment. However, you may be able to get your flooring back to normal, depending on how much moisture damage there was and how quickly you took care of it.

If the cupping persists after you have completed this step, you may need to replace your floor or sand it.

③ Take Out All of The Furniture in The Room

Before starting any repairs, removing all furniture and vacuuming the floor are important. This will ensure that no nails, dirt, or debris could interfere with your repair process.

④ Sand the Floor

This is the most time-consuming step of fixing hardwood cupping. It would be best if you do it with care and precision to ensure that the floor is even and level.

Start by sanding down the high points of the planks using a sander with coarse grit. The goal here is to reduce the peaks and create a uniform surface. Once you’ve sanded down the high points, move on to the low points. With a finer grit, sand in the direction of the grain to smooth out the cupped areas.

Once you have sanded down the entire floor, you may need to sand it again with an even finer grit to make sure that everything is perfectly smooth.

⑤ Apply a Wood Floor Finish

Once you’ve finished sanding the floor, it’s time to apply a wood floor finish. It will keep the floor in pristine condition and prevent damage.

Start by applying a coat of sealer, followed by several coats of finish. Make sure to follow the manufacturer’s instructions for each product and let each coat dry completely before applying the next one. Once you’ve applied the final coat, leave the floor to dry completely before putting the furniture back in.

⑥ Call A Professional

If the problem still exists after trying to resolve it on your own or if you are unsure about doing so, you may employ a professional. A flooring specialist will be able to inspect the floor and advise you on the best solution. They may also be able to fix the cupping if it is repairable or suggests a more suitable option, such as replacing your wood floors.

⑦ Maintain the Floor

Regularly sweeping and vacuuming will help remove dirt and debris, while occasionally mopping with a pH-neutral cleaner can help protect the finish from wear and tear.

Make sure to check for moisture levels periodically, and if you notice any signs of cupping or warping again, address the problem as soon as possible. This can help prevent minor issues from becoming bigger problems in the future.

Tips For Preventing Wood Floor Cupping

As a homeowner, there are certain precautions you can take to prevent wood floor cupping:

Control the Humidity in Your Home

Too much humidity in your home can lead to various problems, including wood floor cupping. Conversely, low humidity can lead to static electricity, dry skin, and cracked wood. There are a number of ways to control the humidity in your home, including using a dehumidifier or humidifier, opening windows on dry days, and running the exhaust fans in your kitchen and bathroom.

Cover Your Floors

Putting area rugs on the floor can help protect them from wear and tear and moisture damage. Be sure to use mats in high-traffic areas of your home, such as entryways or near sinks and toilets.

Use a Vapor Barrier

When installing new wood floors in a damp area, it’s important to use a vapor barrier to prevent moisture from seeping into the subfloor. A vapor barrier is a sheet of plastic that acts as a waterproofing layer between the subfloor and your flooring.

Clean up Spills Quickly

If any liquid is spilled on your wood floors, clean it up as soon as possible. This way, the likelihood of water entering the floor, which can cause cupping and warping, is reduced. Once you’ve wiped up any spills, you should dry the surface thoroughly as soon as possible.

Refinish Floors as Needed

If your floors start to look faded or worn down, it may be time to refinish. Refinishing involves sanding and applying a new finish, which can help protect the floor from wear and tear. Be sure to use the right products and techniques when refinishing your wood floors to ensure the best results.

Following these tips and taking proper care of your wood floors can help prevent cupping from occurring in the first place. Of course, if you do experience cupping in spite of your efforts, it’s always a good idea to contact a flooring specialist for assistance. They can help immensely by offering guidance and input toward a solution.

Final Words

Wood floor cupping is a common problem, but it doesn’t have to be a difficult one. By taking the right steps, you can fix the issue and ensure your floors look as good as new. Be sure to check for moisture levels regularly and take action if any changes are detected. Therefore, if you take the proper precautions, you can ensure your wood floors remain in optimal condition for years to come.