Floor Cupping: What You Need To Know (2024)

Even though hardwood floors are very durable, you can still see problems from time to time. It’s never fun to walk into a room and notice something off about your flooring—especially if the damage is obvious, as is the case with cupped floors. Fortunately, floor cupping doesn’t have to mean the end of the world, or even the end of your beautiful flooring. This issue is relatively common for owners of both solid and engineered hardwood flooring. When you understand what’s happening and what caused the problem, you can do your best to fix your floors and prevent cupping from happening in the future. Do right by your gorgeous hardwood with this overview of what you need to know about floor cupping.

What Is Floor Cupping?

Cupping is a wood floor’s natural reaction to moisture. After all, both engineered and solid hardwood consist of real wood, which warps when it absorbs water. When water seeps into a plank of wood flooring, the side of the board closest to the moisture will expand. Cupping occurs when the edges of the board are higher than the center of the board, creating a concave shape. In addition to ruining the appearance of a room, cupped floors can lead to serious structural problems. If the wood continues to expand and cup, it can result in gaps between the floorboards. This creates further issues once the wood contracts, as the damage might cause it to buckle away from the subfloor. The individual planks may also start to crack or splinter if they can’t settle back into their original shape. If you find cupped floors in your home, make sure you address the issue quickly to avoid further damage.

Common Causes of Wood Floor Cupping

If you want to address the problem, you need to know about the common causes of floor cupping. The root cause of floor cupping is moisture. Wood is a porous material, which means it easily absorbs water. This includes both solid and engineered hardwood, though the plywood core of engineered hardwood is more resistant to changing internal moisture content. However, even though engineered hardwood holds up better against water and moisture, it can still experience cupping. When you understand where this water comes from, you can take steps to prevent it from damaging your flooring.

Humidity Levels

Humidity plays a huge role in the upkeep of your hardwood floors. Wood will try to match its internal moisture content to the moisture content of the air around it. This means that, in high humidity, your wood floors will absorb more moisture, causing them to expand and cup. On the flip side, low humidity will cause your floors to dry out and shrink. The humidity levels in your home likely change naturally from season to season, especially if you live somewhere with humid summers and dry winters. Fortunately, cupping caused by humidity is often less severe and may even correct itself when the season changes.

Subfloor Moisture

Another common culprit of floor cupping lies beneath the surface of your room. Moisture can enter your wood planks through the subfloor. This often occurs in homes with basem*nts or crawl spaces that are more humid than the rest of the house. Water damage throughout the subfloor—often due to leaky pipes or a similar issue—can also creep into your floorboards from below. The subfloor is a major component of your flooring, so make sure you prepare it properly before you begin installing your hardwood flooring. This means cleaning and thoroughly drying the subfloor so that you can eliminate moisture issues before you lay down your first planks.

Leaks and Spills

Wherever there’s a leak or spill, there’s a chance that water damage will follow. Safeguarding against spills is a routine part of hardwood flooring maintenance. If something spills, be sure to clean it up quickly and make sure it dries completely. Keep an eye on mudrooms and entryways, which might see a lot of water as people make their way indoors on wet days. Unfortunately, you won’t notice every spill. The areas around sinks, dishwashers, and other water-based appliances are particularly dangerous. Leaks can also occur beneath the surface, around pipes and other parts of the plumbing system. If you notice cupping in your floors, but you can’t find the source, you might have more significant water damage in your home. This can lead to mold and other issues that go beyond your flooring, so be sure to locate and address the problem as soon as possible.

Improper Installation

Some causes of floor cupping can originate from the original installation. As mentioned above, preparing the subfloor is key to functional, long-lasting hardwood floors. If you install your wood flooring while the subfloor is damp, it can cause moisture-related issues down the road. You should also take the time to ensure your floorboards attain a stable internal moisture content level that will last for years to come. One example involves air conditioning. When you install and use air conditioning, the room’s humidity levels will change—and the moisture content of your wood floors will change with it. Lay down your floorboards when the moisture levels in the room reach steady levels.

How To Fix Wood Floor Cupping

If you find cupping in your home, the first thing you should do is locate the source of the problem. Drying out the floor without addressing the issue only ignores the long-term problem. To truly fix it, you must get to the source of the water damage. Once you’ve addressed that, you can try to get your wood floors back to their original beautiful state. For minor cupping, the fix might be as simple as returning the room to its normal humidity levels with a dehumidifier. For more significant damage, however, you can invest in a professional drying treatment that will return your floorboards to their normal shape. Never sand cupped flooring, as it can create more problems once the wood contracts again. Finally, keep in mind that cupping occurs on a board-by-board basis. Even if part of the floor is beyond repair, you may only need to replace a couple of boards.

Owning hardwood flooring is a big responsibility, but the results are worth it. If you’re ready for rich, elegant floors in your home, check out our American black walnut engineered wood flooring or any other fantastic collections today.