Cupping is a sign of moisture from below. The bottom of the wood is moist and expanding more than the drier top, hence a cup shape. The fact it is over your entire floor would indicate you have poor moisture control in your basement, crawl or slab. You did not mention what is under the floor.

In 35 years I have never seen wood delivered wet, that is above 6% moisture. I have seen it become wet. If the floor was installed wet you would have gaps, not cupping, between the boards as it would shrink as it dried out in your climate controlled environment.

We have had several floor experts look at the floors and crawl space. They have found no evidence of excessive moisture, mildew, leaks or water. We did ,however, discover that the original humidifier in the house never worked. After a rainy fall, we noticed the cupping. Could the rainy seson and the lack of humidity inside the house be a cause of the cupping. Do we need to install fans in the crawl space?

We have had several floor experts look at the floors and crawl space. They have found no evidence of excessive moisture, mildew, leaks or water. We did ,however, discover that the original humidifier in the house never worked. After a rainy fall, we noticed the cupping. Could the rainy seson and the lack of humidity inside the house be a cause of the cupping. Do we need to install fans in the crawl space?

Crawl spaces are notorious for moisture problems. The best are now being built with climate control. Many have problems caused by settling of the fill allowing water to drain into the crawl or downspouts not directing the water away from the foundation. We find inadequate ventilation on most. Often the ground cover (6mil.) plastic is torn up by the trades and not repaired. In our area open soil in a 1000' crawl can release up to 8 gallons of moisture a day and much of it goes up into your floor. In other words there are a host of potential issues.
The houses humidifier is important to help keep the floors from drying out in the winter but is not the cause of your current issue. The humidity level ideally is within 35 - 55% range year round.
You need someone to seriously address your moisture problem. I do not feel those who have looked at it really know what to look for.

Wood changes size and shape with moisture movement in and out.

It never stops, no matter what finish is applied.

Chapter 3 of the USDA Wood Handbook covers wood movement with moisture.

Figure 3-3 shows how shape changes.

Here is a link that might be useful: Wood Handbook, Chapter 3

I concur with the previous posts - sounds like moisture entering the wood from below, which would cause the long edges of the boards to lift - and create a cupping condition. You might also check to see that there is proper space for the floor to "Move" around the perimeter. If you pull up a section of shoe molding or a section of base trim around the perimeter, you want to make sure that there is an expansion gap that the wood can move into during the high humidity portions of the year. If the wood binds between the plates on either end of the floor, it could cause an increase in stress (compression) of the boards and result in a cupping action. (I doubt this is the case though) My money is on excess moisture coming from below!

"You might also check to see that there is proper space for the floor to "Move" around the perimeter. "

Unless the floor is engineered and moves as a single large piece (floating) the movement at the perimeter is no larger than the movement in the field.

Cupping depends on the grin orientation in the wood (how it was oriented in the tree) and how much the moisture content has changed since installation.

i am curious about whether you fouond a solutio

I am having a similar problem

@kschuessler - you are welcome to start your own thread with photos. My suggestion would be to post your problem on a flooring website where dozens of flooring professionals are always lurking, waiting to help with flooring concerns.

www.thefloorpro.com is a great site that will get you several people posting inside of 24 hours.

If this is a new floor or a new problem, you are welcome to have your floor inspected by a National Wood Flooring Association Certified Flooring Inspector. They are not cheap, but they will find the reason for the issue. Most people don't go to this effort unless they are looking to lay blame (ie. looking for someone to pay for their floors to be repaired/replaced)...but it could be useful to find out what the cause is so that it doesn't happen again.

Good luck.

We had natural hickory hardwood floors installed throughout our home ~4 years ago (3500 sq feet). We have a crawl space. We have noticed cupping of the floors (first floor) occurring gradually over time and were unsure why this was happening. It does not appear that the floor installers placed a vapor barrier directly underneath the flooring. We were advised recently by a local contractor to have a vapor barrier installed in our crawl space (which we are planning on having done very soon) to decrease the amount of cupping that is occurring. A few questions I had regarding this are:

1. Will a vapor barrier in the crawl space prevent cupping from occurring in the future? We may have the floors sanded, but if cupping is going to occur again, this may not be worth the expense.

2. We have a 2-story house and although cupping is not too bad on the second floor, it is fairly significant in the living space above our garage - is it possible to place a vapor between the ceiling of the garage and the floor above it to decrease the cupping that is occurring there?

@nikki1307 - I'm sorry to say but you needed to have the vapour barrier in the crawlspace BEFORE the floor was installed. Sorry but this is not the fault of the flooring installers. A General Contractor (who is INSTRUCTED to investigate the crawlspace and correct it prior to flooring being installed) could have caught this.

Now that this has happened, you will need to get the vapour barrier over the earth in the crawlspace QUICKLY. The garage space is another problem. Garage "slabs" (concrete normally) rarely have vapour barriers installed under them. Therefore the concrete in the garage will be allowing water vapour through at a rate that is ALMOST as bad as the crawlspace.

When applying vapour barriers to a CEILING in a garage, you will need some help. The one thing we try to avoid is a "double" vapour barrier. That's a bad situation. You will want to contract a moisture remediation company (when you deal with the crawlspace) to help with the garage ceiling.

As for what the wood will do "after" the moisture has been dealt with, it will take TIME. Lots and lots of time. You will apply the vapour barriers (possibly a dehumidifier in the garage to help you if you can't get a vapour barrier on the ceiling....wood does NOT like plastic sitting next to it) and then wait.

The wood will correct a LITTLE bit...maybe 25% - 50% better. It takes a LONG TIME for wood to LOOSE moisture. Almost TWICE as long as it takes it to GAIN moisture. So if this has been going on for 4 years....you can almost certainly double that time to lose it.

I would give it a few years (like 2) and then look to see how much the wood has corrected. You don't want to do ANYTHING to it until you are CERTAIN that the change in appearance is "finished" changing.

Once you have waited another 2 years (or so...it isn't set in stone) you can then go ahead and have it sanded and refinished. Once it has STABILIZED (this is SUPER important) then the chances of it changing and cupping again are VERY slim....

Until another moisture issue pops up. Then all bets are off - of course.