What You Need to Know About Peaking, Buckling and Cupping in Wood Floors

Keeping wood floors beautiful and strong is a task. While modern wood floors are designed to be durable, homes are filled with “little threats” that make them vulnerable to damage. Everyone wants to protect their investment after adding wood floors to their homes. That’s why knowing about peaking, buckling and cupping in wood floors is essential. While these common flooring issues are sometimes used interchangeably because they create similar visual problems, they are actually very different flooring issues with very distinct underlying causes. First, let’s talk about why floors encounter these problems. Misshapen, damaged floors can happen due to:

  • Improper preparation.
  • Improper installation.
  • High humidity levels.
  • Exposure to moisture.
  • Inferior flooring products.

When installing new flooring that you want to preserve for many years, it’s important to know how to prevent peaking, buckling and cupping because nearly every home has the potential for all three. If you’ve noticed that your floorboards aren’t sitting properly in a home that already has wood floors, it’s important to know the telltale signs of all three common flooring problems to ensure that you’re planning the right fix based on the true underlying cause. Here’s your quick guide to the basics of floor peaking, buckling and cupping.

What Is Peaking in Hardwood Floors?

When floorboards don’t have anywhere to “go” when they expand, they will form peaks on your floor. Considered an “expansion issue”, peaking can be a very unsightly problem that also happens to be a trip hazard. Peaking happens when the edges of the floorboard stick up higher than the rest of the board. You will notice a distinct concave appearance in your floors if peaking is an issue at your home. Peaking actually appears very similar to a problem called cupping that is the result of moisture beneath the floor. However, peaking is always caused by pressure that is making the boards expand.

Peaking is usually the result of improper installation. The issue grows worse over time because the improper installation actually causes pressure to accumulate over time. The easiest way to prevent peaking is to ensure that there’s plenty of space between floorboards during installation. This will allow the boards to naturally expand and contract based on the humidity levels in a home without any distortion taking place. It’s also important to keep proper distance between the edges of floorboards and walls because a tight fit there can create the same issues with distortion.

What Is Floor Cupping?

Cupping occurs when the edges of a floorboard tilt up higher than the center of the board. You’ll see a distinct concave shape that’s very similar to peaking. While the problem may start off small, cupping can continue to get worse until you have huge gaps that create unsightly spaces between floorboards. There’s also a danger that floorboards that are stressed enough will actually begin to splinter and crack. Once this occurs, the floorboards can no longer return back to their original shape and positioning.

While cupping appears very similar to peaking to the untrained eye, these are actually two very separate problems. While peaking is a pressure issue, cupping is always a moisture issue. Cupping happens when moisture levels change in a room. As moisture levels in a home increase, wood boards tend to swell. If floors are installed properly, this minor amount of swelling shouldn’t have a big impact. However, factors ranging from improper installation to extreme moisture can override the normal expected performance of wood floors.

What Is Floor Buckling?

Buckling is the term used to describe rising, humps and unevenness in wood floors. It occurs when your boards don’t “bounce back” to their original shape and positioning after undergoing the normal, natural contractions and expansions that take place with hardwood floors. The easiest way to know that your floor is buckling instead of cupping or peaking is that the floorboards go upwards in a convex shape instead of bowing in a concave shape.

The most common root cause behind buckling is not giving new floorboards time to acclimate to a home’s humidity levels before installation. Ideally, stacked wood flooring will be placed in the home prior to installation to allow it to “expand” or “shrink” to its true size. This will allow the installer to use accurate spacing. Another big cause of buckling is simply failure to put down a moisture barrier during installation.

Can Peaking, Cupping and Buckling Be Reversed?

The answer depends on the severity of the issue. In most cases, remediation can be done right away to help you avoid the need to replace your flooring. However, letting the problem go on for years without taking action could irreversibly damage your floors. It’s important to know that wood naturally soaks up moisture. While this shouldn’t cause you to abandon wood flooring as a choice in your home, it is important to understand how wood’s relationship with moisture will impact every aspect of installation and maintenance. Here are some tips for managing moisture at your home:


  • Acclimate new flooring to your home before installing it. Let the flooring stay in the area where it will be installed. This will ensure that you’re spacing your floor based on its “true” size to prevent future warping when the boards run out of room.
  • Prior to installation, check the moisture of your subflooring. If you notice any water damage on the subfloors, bring in a plumbing expert to identify any potential leaks that could damage your new floors. You should also take time to properly clean and dry your subflooring prior to putting down your new floors. Inspect your crawl spaces if you see signs of moisture because a “hidden” moisture issue could be to blame!
  • If you notice cupping or buckling, try your best to identify where moisture is coming from in your home. It’s possible that you have a leaking pipe or appliance that you haven’t noticed.
  • Control humidity levels in your home. First, use a moisture monitor to know where you stand at all times. Next, consider using a portable or centralized dehumidifier on high-moisture days. You may be able to reverse cupping damage using nothing more than a dehumidifier.
  • While there are many great tips and tricks for cleaning hardwood floors, you should only use the products and techniques recommended by the flooring manufacturer. Even something as simple as a wet mop can introduce excess moisture into your floors that can cause cupping and buckling.

It’s not a forgone conclusion that floors will need to be replaced just because they’ve experienced peaking, cupping or buckling. However, quick action is required to preserve floors once it’s obvious that something is wrong. In some cases, sanding floors to even out peaking and cupping is an option. However, replacing wood floors is sometimes the only way to restore beauty and function to a space.

Final Thoughts on Peaking, Cupping and Buckling in Floors

Stopping peaking, cupping and buckling in floors is something that starts long before floors are installed. It’s important to prepare both the materials and installation area prior to installing new wood floors to avoid any “surprise” expansion. Choosing wood flooring that is more resistant to moisture is also a good option if you live in a high-moisture environment. When you come to Atlas Floors for the best flooring, we’ll help you do just that, so contact us today! Lastly, monitoring moisture levels is essential for ensuring that long-term damage isn’t being done due to excessive moisture. While that may sound like a tough task, simply using a moisture meter to stay on top of the conditions in your home is really all that’s necessary to avoid common causes of flooring damage.

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