Wood Floor Cupping & Other Common Problems: Spotting the Trouble

The beauty and elegance of hardwood floors are undeniable. They are a testament to nature’s splendor, meticulously crafted into pieces that add value and charm to any space. However, like any prized possession, hardwood floors have their vulnerabilities.

Factors like moisture can spell disaster, leading to issues like cupping, crowning, and buckling. But what if you had the knowledge and tools to prevent or address such problems promptly when they arise?

wood floor cupping failure
Dive into this comprehensive guide where we unravel the intricacies of wood floor problems, their root causes, and how, with a simple tool, you can ensure your floors remain a stunning centerpiece for years to come.

Installing hardwood flooring is hard, thoughtful work that, if done properly, can yield lifetimes of warmth, elegance, and beauty in a home or commercial setting. As you eagerly anticipate a successful installation, be aware that problems such as warping, buckling, cupping, and crowning can really ruin your floor and your dream.

Fortunately, there is a way to mitigate the risk of these depressing conditions. A little bit of knowledge and one good tool can help you. Read on and let’s get started.

First, many homeowners and even pro flooring installers may not realize they need to measure the moisture content (MC) before, during, and yes, even after installation. In fact, commercial property owners and homeowners should never stop monitoring the MC of their hardwood flooring if they wish to keep it pristine, beautiful, and flat.

Wood Expands or Contracts According to the Season

This happens because wood loses or gains moisture depending on the relative humidity (RH) and temperature of the surrounding environment.

Here’s how it works…

Wood Shrinks as Its Losing MC

When you turn up the heat in the winter, the RH level inside your home decreases. This causes hardwood flooring boards to lose MC and shrink. In fact, you might even see spaces appear between boards during the winter.

Wood Expands as Its Absorbing MC

When you turn off your heat in the spring and open the windows your hardwood flooring boards will begin to expand again. The spaces between the boards that were there during the winter will probably now disappear.

So, the expansion and contraction of hardwood flooring are normal. It’s just something that happens as the seasons and RH change. You should expect to see gaps form between wood flooring boards during the winter. However, those gaps will probably close naturally during the spring.

Use a Moisture Meter to Monitor Your Wood Flooring

All owners of wood floors should invest in a high-quality wood moisture meter. Moisture meters measure the MC in wood and when it comes to professionally installing wood flooring material, they’re a valuable tool of the trade.

No qualified and experienced contractor would ever install a wood floor without a moisture meter. This is because prior to any installation, the wood must reach its ‘equilibrium moisture content’ or EMC. This is a point of balance between the MC of the wood and the RH of its ambient environment.

If the wood isn’t allowed to reach its EMC prior to installation, problems could develop later.

Wood flooring owners should continue to monitor the MC of their wood flooring after the installation as well in order to avoid any moisture-related problems.

The following list of problems isn’t exhaustive. However, it does cover some of the more common ways moisture changes can negatively affect wood flooring.

Whether you’re an installer or a homeowner, knowing what causes wood floors to fail is the first step towards preventing failures.

What causes wood floors to cup

What Causes Wood Floors to Cup?

Cupping in hardwood floors is caused by changes in moisture levels, whether decreases in the air RH above or increases in moisture from below. Other causes of hardwood floor cupping could include situations such as basement plumbing leaks that allow moisture to migrate up into the subfloor and into the wood flooring or the heat from a wood stove that dries out the air in the environment.

hardwood flooring moisture problems

Watch our hardwood floor problems – common causes video series.

Whatever the cause, a moisture imbalance develops from the bottom of the floor to the top. This imbalance causes each plank to develop a concave shape with pronounced raised edges.

When you see cupping, you need to identify the moisture source. Is it due to low indoor RH or a plumbing leak? Once you’ve identified and controlled the moisture problem, you might be able to reverse the cupping.

Minor cupping is a natural reaction to moisture and shouldn’t be a concern. However, severe cupping indicates a serious moisture imbalance.

As the saying goes, an ounce of prevention is worth a pound of cure and this definitely applies to wood flooring. Everyone who owns a wood floor should use a moisture meter on a regular basis to identify moisture changes that can lead to cupping.

What causes wood floors to crown

What Causes Wood Floors to Crown?

Wood floor crowning is the opposite of cupping and happens when the center of the board is higher than the edges. Like cupping, wood floor crowning happens because the boards are exposed to a moisture imbalance over an extended period of time.

Crowning can also be caused by previous floor cupping. Here’s how that happens…

A cupped floor needs ample time to dry. If the floor is sanded while the boards are still cupped, the sanding process will sand off only the raised edges of the boards. When the floor dries and returns to a normal MC, these sanded edges will be lower than the center of the boards.

What Causes Wood Floors to Buckle?

Buckling of hardwood floors occurs when the wood actually pulls away from its subfloor lifting up to several inches in one or more places. Buckling is an extreme reaction to moisture and fortunately, doesn’t happen very often.

Buckling is often due to flooding and happens after hardwood flooring has been submerged for some time. However, buckling can also be caused by insufficient nailing, incorrect nails, incorrect construction of concrete subfloors, or failing to use a vapor barrier (also referred to as a moisture barrier) or vapor retarder.

With glued floors, buckling can be caused by incorrect mastics, inadequate mastic transfer, subfloor separation, or subfloor contamination.

Fortunately, even buckled wood floors can sometimes be repaired instead of totally replaced.

Any moisture imbalance can cause problems with wood. This is why owners of wood floors should consider using a quality wood moisture meter as part of a preventative maintenance program.

Other Common Problems with Wood Floors

Spaces Between Boards

We touched on this above. When it comes to wood, almost every type of flooring endures some expansion and contraction as seasons and humidity levels change. For example, when homes are heated during the winter, humidity levels drop, boards shrink and spaces appear between them.

During any dry season, cracks can easily develop to the thickness of a dime on a typical solid 2 1/4″ oak floor. Light-colored woods will make these cracks appear even larger.

These spaces are to be expected and usually close up when moisture returns to the air. However, can use a humidifier to add moisture to the air during a dry period.

How Do You Fix Cupped Floors?

If you see serious cupping, you’ll need to first identify the source of the moisture. Once you’ve taken care of it, the floor should dry out by itself over time. You can use fans to speed things up, if necessary. Remember, minor cupping is a perfectly normal reaction to a change of humidity in the environment.

If you’re interested in learning more check out our article about if cupped wood floors can be fixed.

Will Wood Floor Cupping Go Away?

It might. Minor cupping is not a problem and is something that you should even expect. When the temperature and humidity change, the cupping will probably go away.

Major cupping caused by water damage is another matter. However, it’s possible that once you’ve determined the source of the moisture, the floor will dry out eventually and the cupping will disappear. However, you may need to sand and refinish it though.

Will Cupped Floors Flatten?

Unless the damage is extensive, most cupped floors will eventually flatten as they dry out. As we’ve pointed out, minor cupping is normal and to be expected. It will go away as soon as the weather changes. However, even more serious cases of water damaged floors can sometimes be resolved by simply allowing the floor to dry out naturally.

Always Use a Moisture Meter

Whether it’s a building, a wood floor, or another type of wood product, if you want to maintain the value of your investment, you’ll need to spot moisture problems before they occur.

Wood moisture meters have come a long way since we formed Wagner Meters in 1965. Today we carry wood moisture products for lumber mills, building inspectors, installation contractors, wood hobbyists, and the owners of wood floors.

Yes, our moisture meters are designed for professional flooring installers and building inspectors. However, homeowners will find Wagner Meters’ quick scan capabilities useful for regular home maintenance.

Wagner Meters’ non-damaging pinless technology allows any user to easily, quickly, and accurately determine wood MC.

Free Download – 4 Reasons Your Hardwood Flooring Failed

Last updated on March 20th, 2024


  1. USVintage Wood says:

    Thank you for sharing this knowledge. Knowing these will help us to take care of our wood floors.

  2. Thank you for posting excellent content to help us maintain our hardwood floors’ quality. This is a great help to us. Keep on posting!

  3. Aaron says:

    We played a hardwood floor
    We climatized the timber for quite a while
    Two days later the sun hit the boards just inside the sliders and cracks appeared in some of the boards and slight cupping
    There is no moisture

  4. Mark says:

    Hi, I have an issue with brazilian hardwood floors that are crowning. Noticeable over the last year. It’s been low RH in our house. Maybe 40%. Crawl space gets to 70%. If there was an issue with crawl space humidity I thought this would cause cupping. Is there something I can do about this?


  5. M. S. Weiner says:

    I like to leave the patio door open on nice days to get some air in, or rather I should say our cats loves it. What I would like to know is what is the maximum humidity in the outside air should there be to stop any cupping to the floors? The floors are over 25 years old and are in extremely good condition and I would like to keep them that way. I haven’t done a thing to them. They have never been touched since they were installed.

    • Jason Wright says:

      M.S. Weiner,

      For a complete explanation of wood, humidity, and how floors react to it, I would refer you to NWFA.org. (National Wood Flooring Association) This site will answer your questions. Thanks for writing in.

  6. Robert Workman says:

    Nice! The information I got through this blog has really helped me in understanding this Wood Floor Cupping & Other Common Problems That was something, I was desperately looking for, thankfully I found this at the right time.

  7. Mike Germano says:

    I have a newly installed oak variable plank wood floor installed throughout my home on the first floor. It was installed by a professional. About one month after installation the wood in the kitchen area of the floor begin to cup. I told the installer and he felt it was possible moisture in the wood. He re-sanded the floor and it looked great. Four months later the floor has again cupped in the same area and it is worse than before. I had he re look at it and he tells me it had to be done by water damage. I was told to check for pipes etc that could be the culprit. The kitchen area is in the center of the home and was a complete renovation. I have no pipes that could have caused this. In addition the basement below the kitchen floor is fully exposed as this is a 80 year old home. I would see any pipe issue and there is none. My question is that both Air conditioning air handler is directly below this area and my gas furnace is located closely below the kitchen. Where as I do not see any water issue I am wondering if these items could be a cause for my problems. How will a wood water meter help me solve this riddle.


    Mike Germano

    • Jason Wright says:


      I’m very sorry to hear about your issues with your wood floor. Cupping, (dry or wet) wood floors can be caused by humidity, lack of humidity, temp, & water. Wood is hygroscopic, so it gains or loses moisture in your home seasonally.

      How our 950 moisture meter works is it has a hygrometer built in to read temp, humidity, and calculates your the EMC (Equilibrium Moisture Content) of what your wood floor should be. This is just a few options available with our meters.

      What I would suggest is to visit: http://www.nwfa.org.

      Here you can find a certified WOOD expert. Hire only an NWFA certified inspector. They will evaluate your conditions and write you a complete report on the findings.

      I am happy to go over our meters with you upon your request.

      Hope this helps,

      Jason Wright

  8. Zoe Campos says:

    Thank you for reminding me that doing preventative measures is better than cure even when it comes to flooring. We’re seeing some fine lines around our flooring and we have observed that there are parts that extend up to our walls. It might be better to call professionals and see if we need any floor or foundation repair services.

  9. Sonia Lopez says:

    i recently installed bamboo flooring in my living room, i notice it started to buckle up in several areas, is this cause by humidity or maybe a leek under to house? what should i do to fix issue?

    • Eric Wagner says:

      It’s a moisture problem of some sort. Either the subfloor, the flooring itself, or the ambient environment. Is it over concrete or a wood-based subfloor? The Rapid RH will test if concrete, an Orion moisture meter if wood-based. The Orion moisture meter will test for bamboo flooring moisture content before installation to verify it’s at a proper moisture content and ready to install. And finally, our SmartLogger will allow you to measure and monitor the humidity in the surrounding air to make sure your ambient environment isn’t the culprit.

  10. Karen Im says:

    Hello, we recently bought a brand new home and tore out the ugly carpet and installed beautiful new hardwood floors. We noticed lately that we are seeing some strange dark lines that look like worms developing on many of the planks. We were concerned so we had two termite in spite inspectors come out as well as the contractor. Luckily it’s not termites and it wasn’t an installation issue. One thing we did notice is that the areas with the worm like stains are higher in moisture than the rest of the normal planks. Do you know what is happening? Can it be reversed or is this a bad batch of wood? Help!! We installed white oak planks.

  11. Michael Valvero says:

    Renovating a home with original hardwood floors. They are over 100 years old. Some in really good shape. We removed plaster lath from the first floor. Big demo project. The plaster dust obviously dries the air. So we have large openings between boards forming and some cupping. Is there a good way to fix? Is the something I can coat the boards with to solve?


    • Jason Spangler says:


      Thanks for the questions. Before you look for a “fix”, you are better off getting the environment back to its original temperature and relative humidity as soon as possible and then leave it to see how the wood reacts. Keep in mind, wood can dry out and shrink because of dry air, but it also does the opposite and absorbs moisture and grows when the air is moist. Doing this may pretty much solve the problem.

  12. Ryan says:

    We are installing new 3/4′ nail down prefinished hickory hardwood flooring on our second level to finish off a kitchen remodel. During the remodel we had to tear some of the basement ceiling out to run plumbing lines being we moved our sink location to a new island. If I lay the hardwood flooring first will it be affected by the spray texture and painting done on the basement ceiling which is directly below the new floor?

    • Jason Spangler says:


      This may have an impact on the hardwood installed above. I personally wouldn’t install the hardwood until the environment below is back to where it will be once the remodel is complete. Good luck.

  13. Allison says:

    Hello- need advice! We built a new home last year with 4” white oak. During our first heating season, we have seen some gaps in the wood as you described. But in several areas the gaps are much wider than a dime. Any idea of the cause and any way to correct? Could this have been an installation issue? The moisture level was measured and the wood was left to acclimate in the house well before install. Thanks.

    • Jason Wright says:


      In actual practice, shrinkage and swelling may be diminished by the boards’ proximity to each other, installation methods, fastening systems and moisture interactions from the substrate. These can all influence how an installed floorboard performs when it changes MC.

      The ideal average moisture content for flooring installation can range from extremes of 4-13% depending on many variables, including geographic location and time of year. Additionally, a wide range of conditions can be experienced between individual job sites in the same locale, such as an ocean-front or lakeside home versus one that’s a few miles inland. Before installation, the flooring product should be identified as being compatible with the area in which it is to be used. (EMC The moisture content of wood below the fiber saturation point is a function of both relative humidity and temperature in the surrounding air. When wood is neither gaining nor losing moisture, equilibrium moisture content (EMC) has been reached.)

      Wood flooring will perform best when the interior environment is controlled to stay within a stable environment and the wood is installed at a moisture content corresponding to those interior conditions. Most wood flooring manufacturers dry their flooring to 6-9% MC, which directly coincides with a relative humidity range of 30-50% and a temperature range of 60 to 80 degrees Fahrenheit. This 6-9% range is likely to be the average of all types of wood products used in a normal household environment, assuming common heating and cooling equipment is used to ensure human comfort.

      Wood flooring is constantly exposed to both long term (seasonal) and short-term (daily) fluctuations in relative humidity and temperature of the surrounding air. Thus, it is always undergoing at least slight changes in moisture content. These changes are usually gradual, and short-term fluctuations tend to only influence the surface of the wood flooring. The rate at which a wood flooring product reacts to these changes varies by species and construction. Note that moisture content changes can be slowed, but not entirely prevented by protective coatings. Perhaps identify RH in your home and maintain it the best you can annually. Hope this helps.

      Jason Wright

  14. Miss Indie says:

    Thank you so much Jason. I live in England so will find out who the equivalent of NWFA is here. Kind regards

  15. Miss Indie says:

    Hi – 2 weeks ago our solid oak floor warped severely – there was no inclination it was going to happen, we went to work in the morning and by the time we got home in the evening it had warped up by a good couple of centimeters. Overnight it moved more and by the middle of last week fumes started to be emitted (which since the weekend have subsided). Our builders came to have a look and suggested that the glue had reacted with something as there were brown spots on the concrete. The underneath of the wood that had risen was wet with moisture/condensation. There was no pool of water or damp patch. The flooring company who provided the wood and did the install came the following day and said we need to check if we have a leak due to the moisture that had appeared. They said it wasn’t the glue they used and that they had left enough expansion. The builders have said that 2 layers of damp proof membrane were put down when the extension was being done as they knew we were having underfloor heating and a wooden floor. The floor was laid at the end of last August directly onto brand new screed that had been done in the middle of June. Yesterday we noticed a couple more areas have started to warp. What we are baffled with is how water has appeared on top of the screed? We have had no spillages. The main drain for the street runs under the new extension so could that possibly have something to do with it – with the recent bad storms we have had? We have a leak detection company coming to investigate for any leaks (but my water bill has come in and doesn’t show any increased usage). The builders have suggested that because the boards were not glued along the seams that it was not sealed enough and when the floor has been mopped (with recommended wood cleaner so not saturated) the cleaning fluid has gone through the joins and reacted with the glue. Apologies for the long message but it would be good to get some advice as to why the buckling is so extreme and it happened so quickly. TIA!

    • Jason Wright says:

      Miss Indie,

      I sympathize with your situation. After reviewing your comments and looking into causes, problems, and cures, it all seems to come down to one thing: Moisture. At the time of installation the installer should have done moisture testing in the concrete and hardwood. Assuming he has tested the concrete and the wood he would determine if the concrete and wood can live in the conditions given. This is called Equilibrium Moisture Content. (Conditions where the wood can’t absorb, or release moisture) Check with them to ensure the proper steps were taken prior to installation. Assuming this was done and documented, the swift change in the wood is caused by moisture, either topically, or underneath. If underneath, there has to be moisture under the concrete. If topical could be from a spill or possibly a leak above it. The conditions you are describing sound like an “accident” has happened. I would highly recommend an NWFA Certified Inspector visit your home and get a full analysis is completed for you to move forward. Here is the link: https://www.woodfloors.org/certified-inspector.aspx Hope this is helpful.

  16. Douglas Ehrk says:

    I have a closet with Cedar flooring. The ground (dirt) under the house is usually moist in the winter along the exterior home’s foundation from rain. There is a hard pan and the rain will wick under the house, I assume. All summer we have had no rain (this is California) and I have wetness on the cedar flooring right now but only in one isolated area about 2’X2′. There are sprinkler valves outside of the bedroom about 4 feet from the corner where the wetness is. I dug it all up and it is dry around the sprinklers and along the 3/4″ PVC line that goes past the bedroom closet in question. In the mornings there is dew and there are 2 vents in area for the foundation. Could the wood be getting wet from a vent bring moisture in? I have no other signs of water and there is no water in the attic that could be coming down the walls. The sub floor 2X6 tongue and grooves are dry as well.

    • Jason Spangler says:


      Thanks for the question. It’s plausible that moisture would be traveling through the vent, in the air, depending on what the environmental conditions are and the ventilation and cross ventilation situation. If you had access to that area under the house and could place a device like the Smart Logger, you could log the conditions to have a better idea of what was happening. Good luck.

  17. Fran says:

    Hi Jason

    WE bought a 1970’s ranch home last year that had been rehabbed. Had it inspected and there we minor issues with the house (accept for the roof) so we budgeted for it. We also did some cosmetics work including replacing the worming veneered wood floor with hardwood that matched the white oak in the bedrooms. Toward the fall we noticed some cupping in the dining area near our bay window. We called the floor installer in and he was stumped. HE said he knew he cured the floor enough so that could be the problem. I trust this guy, he has rave reviews and he has done hundreds of floors in our area. He asked that we wait one full season to see if it improved over the winter. We agreed.

    Over the winter the cupping went away so we thought it was a fluke. Unfortunately, it came back the following summer only now it has travel further into the room and into the adjoining open kitchen.

    We called the floor guy back. We are all scratching our heads. So my husband opened up the window seat of the bay window. When they built the he window they built it over the existing deck which is beginning to sink. It looks like we have a drainage problem in that area, specifically on the right side. He also lifted the underpayment in the window seat to expose the joists and insulation. The insulation was slightly wet near the front of the window. Outside the window on the bottoms is a stone facade which was pulling away from the porch in the spot where the porch is sinking so my husband air I think out with fans and injected spray insulation with a wood trio and then sealed it with rubber cement caulk to get us through the winter. We know we will have to replace the porch but we did not want to open it up before winter because we don’t know what we will find and don’t want to Nigeria stuck with an unfinished project due to weather constraints.

    In the meantime we have gotten dehumidifiers, upstairs and one isn’t he basement to see if taking the moisture out of the air will get the floor to go back. So far no luck.

    My questions are: have you ever uncounted a problem like this? Who would I call to help us determine what is causing this? If the floors are permanently damaged would it be an insurance issue?

    Lastly, we have gotten a meter to measure the moisture in the wood. The exposed decking in the window seat measures 27 but the floor joists against the house measures only 8. The floors near the window are anywhere from a 9-12. They are 6-8 in the other areas of the house not by that window. The humidity in the house ranges from 45-60.

    Thanks for your help.

    • Jason Spangler says:


      Thanks for the detailed background on this issue. Depending on the environmental situation, you can have seasonal fluctuations in floors. Sometimes it’s a matter of obtaining better environmental systems to regulate conditions more succinctly or obtaining better cross-ventilation in basements and crawlspaces. In your situation, exterior drainage may be an issue. I think your best bet would be to have a certified flooring inspector come out and evaluate the situation first hand. You can find one at https://www.woodfloors.org/certified-inspector.aspx Good luck.

  18. Shai says:

    I have recently bought a house, and noticed after a few months of living in it that the carpet in the living room began raising up. I believe one of the floor boards underneath is beginning to crown upwards.
    What should i do?

  19. Scott Jones says:

    Hi Jason, A couple of days ago I discovered sections of 3-4 boards of my stranded bamboo floor had cupped. The floor has been down over 8 months and there is only cupping in this one small area (about 2 sq feet) out of 1900 sq ft. total. I had a sink overflow and I estimate that about a gallon or less of water could have gone to the floor on the other side of the wall directly adjacent to this area (not sure). I also notice a single piece board of bamboo that was against the wall in that area. I left expansion gaps in the entire floor, but it is possible that I missed this one board. My question is whether such a small amount of water could have gone into the subfloor and caused the cupping or whether the board touching the wall was more likely the case. I cut the board back as I was checking the area for any small leaks in the plumbing. Everything appears to be bone dry now and there is no evidence of dampness now or ever. Based on reading some of your other replies, I don’t plan to do anything other than keep eye on it. I would appreciate your thoughts on whether such a small spill could be the issue. Thanks! Scott

    • Jason Spangler says:


      Thanks for the question. Any amount of water could have a negative impact on a wood floor and subfloor, especially if it gets under the floor and can’t ever really be dried out completely. Keep an eye on it and see what happens. Good luck.

  20. Lissa Buckley says:

    I live in Colorado, north of Denver. My dishwasher had a leak, which was discovered right away and the floor was dried. We removed the dishwasher and the next day our hickory floors started to cup. It has been 3 weeks and the floors are starting to go down a little. We did turn off the whole house humidifier to see if that would help dry the floors faster, along with some fans. Our house is going on the market in 10 days, so we are stressing over the floor. How long does it take for the floor to dry out? How long should we wait to refinish the floors, if necessary? Thanks!

    • Jason Spangler says:


      Thanks for the question. I am sure my answer to your question won’t be exactly what you are looking for, but here it goes….it depends! It depends how wet the floors are and how much moisture got under them. It depends on how dry the air in the house is and the air movement across the affected area. In the end, dry, warm, airflow across the surface of the affected area is usually your best bet. The floor needs to be dry for refinish. Good luck.

  21. KAREN says:

    Hi, Happy New Year! I live in north central Illinois not far from the Wisconsin state line. We can have damp and humid to very drying conditions in our homes with the changing seasons. I am a warm weather and fresh air person so spring through summer I prefer doors and windows open, until the temperature gets into the upper 70s or the humidity gets oppressive then on goes the air conditioner. This winter I was going to install all new flooring, after looking at laminate and plank vinyl which look to fake for me decided on expanding budget to wood and have fallen in love with Acacia wood. Here are a few questions I hope you will share some experience or opinion about with me. I have come across the opinion that engineered wood is slightly more stable than solid wood, less expansion/contraction, (better for the climate I live in as well as my budget) would you agree? Secondly, I had a sale associate actually tell me not to get Acacia because it tends to split being an exotic wood not suited for our climate, any opinion? Thirdly, acclimation seems to be such an important part of the installation process, is there a better season/time of year to install wood flooring, depending on where you live? I ask because one sales person, after telling her that I like doors and windows open as much as possible, said that would lead to a lot of cupping and crowning of my flooring with our seasons. I asked if installing in the spring or summer when the wood would acclimate to a higher humidity would be better, and installing a furnace humidifier (which I have wanted to do forever anyways) for dry winters be a solution? She thought maybe, but it would depend on if it was a floating floor or a nail down. Unfortunately she didn’t get to explain. Now of course that just adds to my dilemma, nail down or floating? Any thoughts? I realize I am asking for a lot of
    opinions here but I have saved up for years to do this and am trying to make the best decision for my investment. Thank you for your time. Karen

    • Jason Spangler says:


      Happy New Year to you and thanks for the questions. First, engineered flooring is touted as being more dimensionally stable, especially in varying ambient conditions. My opinion is that ANY product installed appropriately and with realistic expectations will perform appropriately. I knew a gentleman that lived in an area like you speak and he sounds much like you. He didn’t even have A/C and heated with wood, which potentially makes the air even drier. He knew that in the winter his floor would shrink and there were gaps between boards and in the summer those gaps would be gone. That’s what he loved about the solid wood. Again, the floor was installed to accommodate this type of movement. Of course, I wouldn’t recommend this for everyone, but it gives a drastic example of what you speak. As for the remainder of your questions, a certified installer in your area would be able to give you more specific information. I would contact this organization https://www.woodfloors.org/ and look for a qualified installer and discuss some of your other questions with them. Good luck.

  22. jim says:

    Looking at a 4.25″ oak floor. More than 7 years old. never a problem. Had it sanded stains and three coats of an oil base finish. Completed in January. Now there is cupping everywhere (even at a location where new flooring was installed). Old flooring was placed over plywood that was placed on concrete. i saw a vapor barrier at one location. The concrete slab is on grade. At another location a new floor was installed over 2×10 sleepers. Similar concern. Some moisture reading were elevated. Floor spongy at other locations. There was water supply piping beneath the floor that has been abandoned.

    Trying to figure out the cause. Also, can you seal in moisture that wil cause cupping later?

    Thanks you

    • Jason Spangler says:


      Thanks for the question. Anything is possible, but this wouldn’t be anything I have heard about. I am more inclined to think either interior conditions have change, RH% and temperature, or the slab doesn’t have an intact vapor retarder below it, allowing for residual moisture from the soil to enter the slab from below, making the wood floor wetter on the underside. I would reach out to the National Wood Flooring Association at http://www.nwfa.org and find a certified wood flooring inspector in your area to look at and report on the situation. Good luck.


  23. Stephanie says:

    I use a shark steam mop on my real hardwood floors. The floors are 23 years old. We live in North Florida – very hot and humid. I’ve noticed very minor cupping over the past year or two. Could it be from my shark steam mop?

  24. Denise says:

    We installed bamboo floors in our master bedroom. The contractor glued them down according to the specifications. It has been a humid summer and in spit of running a/c the floors are now buckling. We had the contractor come back and he nailed them down in several places. The floor was fixed after the that. We kept ac on and now it’s buckling again. What do we do?

    • Jason Spangler says:


      Thanks for the question and sorry for the problems. Being very simplistic in my explanation, the moisture content of the bamboo has changed since installation. I would recommend you contact http://www.nwfa.org and look for a certified inspector in your area that can help pinpoint the culprit of the problem. Good luck.

  25. Daphne says:

    Hello: I had my waxed red oak floors sanded, stained and refinished. There is cupping that has occurred in the middle of my floor where there is no
    water leak issue that I can find. It’s strange because some of the parquets are cupped while one next to the cupped one
    is OK… I am wondering if somehow the floor guys spilled stain which seeped down through the cracks separating the parquets
    and has now caused the cupping… Since I can’t determine a source for a water leak… I live in an apartment, should I place
    fans or a fan w/ a heater element to blow over the cupped parquet squares. In an attempt to dry out and reverse the cupping?

    • Jason Spangler says:


      Thanks for the questions. Your idea of airflow may be a good idea and, if there isn’t any continual source of moisture affecting the area, stable, continuous room conditions may help it change on its own. If you find this doesn’t help, you may wish to contact a certified inspector to take a look http://www.nwfa.org.


  26. Stephanie says:

    Hi Jason, My father and I returned to our house from our cottage to find the kitchen flooded, and below that the furnace room too. Outside of the kitchen is our dining room with hardwood flooring. 2 pieces have swelled to the point where the gap between has elevated the edges to almost 45 degrees. We had a pipe burst in the ceiling of the basement and that sprayed water up into the subfloor. As we were away, I’m not sure how long the hardwood was flooded. I’m assuming the only option at this point is replacing??

    • Jason Spangler says:


      Thanks for the question and sorry to hear about the troubles. At the minimum, it sounds like the two pieces you have described may need to be replaced. Upon removal of those, there may be more visible sections that need to be replaced proactively. Getting a qualified wood flooring installer or inspector may help to identify the extent of replacement necessary. Good luck.


  27. Eugene Morvant says:

    I live in south Louisiana — our house is 70 years old elevated on cement blocks. The original flooring is oak which we recently covered with covered with vinyl planks. We also insulated the underneath of our house. Since then we have noticed cupping of the original wood flooring. Before we rip up the vinyl planks is it possible that the cupping might flatten during the winter?

    • Jason Spangler says:


      Thanks for the questions. The answer is maybe. If I had to guess though, by insulating the underneath and installing the plank on top, you have altered the woods “normal” environment from the last 70 years and created an assembly where the moisture may have a harder time equilibrating and the wood may not “relax” completely. Good luck.

  28. Tamieke says:

    In our renovation we we polished up some old hardwood flooring but had to pull up some sections damaged boards and replace them. It all looked really great and matched up well. We have since sanded and varnished the total area. After a few weeks we noticed the new boards have cuped. Shall we re-sand the cuped area or is it possible that they will then crown?

    • Jason Spangler says:


      Thanks for the question. First, I would want to know why the boards cupped and do what I could to remedy the situation. The boards may “relax” if the situation is remedied and the cupping isn’t too severe. Sanding the boards, when cupped, thins out the edges and could create varying problems in the future. Good luck.


  29. Marc Vickers says:

    I had a slow leak from under my kitchen sink and I have hardwood floors covered with linoleum. I have severe cupping in the floor. Will I need to remove linoleum for it to be able to dry out? Suggestions.


    • Jason Spangler says:


      Thanks for the question. As far as removing the linoleum, it will be much easier to dry out the subfloor and/or determine the extent of the damage without the linoleum. Good luck.

  30. Nathalie A says:

    Hello, Jason. I’m hoping you can provide advice. I had 3 1/4″ maple hardwood (Lauzon) installed on my second floor last May (2017). I live in southeastern PA, where it is dry in the winter and humid in the summer. I run my A/C at 73 degrees all summer. Within about a month of installation, the floor cupped, just about every plank throughout the entire floor. The installers told me to wait to see if they uncupped during the winter, which they did. Now that its summer again, they’re badly cupped again. It is uncomfortable to walk in bare feet.

    The current RH in my house is about 42%. The installer showed a floor humidity level of 8%. That seems reasonable to me, right?

    After much recent research, not knowing anything about hardwood floors prior to installation, I realize that they only allowed the flooring to acclimate in the boxes for 1/2 day. The owner says that it doesn’t matter because they were kept in a temperature-controlled warehouse. I don’t see how that applies to the RH, etc, in my own home. He says if they replace my flooring, the cupping is likely to happen again. I am at a standstill, not knowing what to do. I do see that a wooden drawer in a piece of furniture has swelled since the winter and now won’t close. Perhaps humidity is a big factor in my house? Yet the humidity level seems to be within normal limits, and every other home I’ve been to in the area does not have cupping, and I know they don’t have dehumidifiers.

    Do I take the safe route and replace with carpet or engineered flooring? I wish I knew definitively if the cupping is a result of improper installation, or just the way the humidity is happening in my house.

    Thanks for your help.

    • Jason Spangler says:


      Thanks for the question. I can’t answer the question of installation proficiency, but I can make a few general observations. For the floor to cup and then “relax”, there has to be changes in the moisture conditions within the house. Now, I don’t know if it is a change in conditions (RH% and temp) on just the bottom floor which is impacting the upper floor, just the second floor, or possibly uniform, seasonal changes throughout the entire house. You question other people not having dehumidifiers and having no issues. Keep in mind, many humidification/dehumidification solutions are integrated into the HVAC systems within houses. Some would probably not even know they were integrated into the system. In certain instances, different homes may also have drastically different efficiencies based on construction practices. Personally, I would need more information before I made a switch in flooring finish and you should be aware that you can still have this same issue even with engineered products. I would want to have evidence, either way, what the RH% and air temp do throughout the year. Knowing this may allow you to just look at improvements that can be done to allow for a consistent environment for you and the floor. Here is a product that will log those conditions over time and allow you to quantify the variations if there are any https://www.wagnermeters.com/shop/smart-logger/. Good luck.

  31. Elena says:

    We just moved to 6 year old home and after few days of heavy rain most of our living room floor boards are cupping. We believe the water could get underneath from the gutter. Is there any simpler solution to improve situation rather than replacing the floor as suggested by technician? This may happen again and we are puzzled.

    • Jason Spangler says:


      Thanks for the questions. First, I wouldn’t fix any symptom (the cupping) until I knew for sure I had fixed the problem. Unless, obviously, there is some eminent danger of bodily harm due to the cupping. If the gutters are thought to be the culprit find out why and remedy it. Then, once you have that fixed and the floors aren’t getting continuously wet, you can see if any of the damage slowly goes away. Keep in mind, wood can absorb and expel moisture, depending on the severity of the damage and length of time. With that, some of the cupping may “fix” itself as the floor starts release the moisture. Good luck.

  32. Sue Cobb says:

    Hi Jason,
    We are considering hardwood (ash) flooring for a mountain home where there is very low humidity, especially in the winter. We are not there all of the time and are wondering if you know of any whole house humidifiers that could be programmed remotely to keep the humidity at a decent, consistent level while we’re away. We have baseboard heaters.
    Thank you.

  33. Valerie Ewing says:

    Eric, we had all new hardwood installed in our renavated home. We are their 4 months, I noticed the cupping right away, my builder said that the wood was tested for moisture and passed. He said it was due to a rainy several days after install. He said there is nothing we can do about it. We are sick over it as it is very noticeable. Is there anything we can do to fix this, will it get better or worse overtime. We spent a lot of money on this renovation and are so upset, the house has an open floor plan and therefore it’s throughout all of the open living area. Any information you have regarding this problem and how to fix it would really help.

    Thank you
    Valerie Ewing

    • Jason Spangler says:


      It may “relax”, over time, depending on what really caused the issue. I would visit http://www.woodfloors.org and find a certified inspector to come out and do a thorough report on the issues, remedies, and causes so you can try to completely understand. Knowledge is power in this type of situation.

      Good luck.

      Jason Spangler

  34. Eric says:

    We have just bought a home, and after taking a hot shower, our wood floor in the kitchen is crowning in one area. Can the boards go back to normal if we find the source of the moisture and let it dry? Or does it have to be replaced ?

    • Jason Spangler says:


      Thanks for the comment. It depends on the extent of the damage. Unless it’s a hazard, the best course of short-term action is probably watch and wait. Good luck.

      Thank you,


  35. MR TOM CORBETT says:

    I have had a leak in the bathroom toliet, valve went drips spread into carpet and under floor boards. There is cupping about 1/8 of boards slight. O have solved the problem, I work away, can the boards dry out in ambient conditions in the flatnaturally over months

    • Jason Spangler says:

      Mr. Corbett:

      Thanks for the comments. With a cupped floor like this, they may not ever go back to their “original” state, but they will probably lessen in their degree of cupping. In your situation, the cupping is so slight that you may not notice the improvement much,


  36. Kathryn A says:

    water spilled on my wooden floor and i have minor cupping as a result. can this be reversed? it is tongue and groove bamboo flooring.

    • Jason Spangler says:


      Thanks for the comment. The answer is maybe, but I would guess it will never be complete as it was originally. No more water issues being experienced, the best chances are to have ambient conditions that are consistent and dry enough to allow the moisture to move out of the floor. My guess is that it will take an extended period of time (months) for you to see the end result.



  37. bert says:

    If I set up tent over damp hard wood floors and put a humidifier hooked to it will it in reversing cupping its in a small area ?

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