Wow, I am sorry about your floors. I would suggest running the A/C with the dehumidifiers until the issue is resolved, then develop a system to maintain a consistent humidity level in your home.

People often forget that one of the main functions of A/C in addition to cooling, is to dry out the air. Maintaining a more consistent year-around humidity level in the home is better for furniture and the home's building materials.

That said, your flooring guy should have allowed sufficient room for normal expansion/contraction to prevent buckling. I hope you get this issue resolved quickly so that you can enjoy your beautiful floors.

Cupping is usually the result of a moisture issue underneath the flooring, not always, but in most cases.

How high did the RH get upstairs?

The homeowner is responsible for maintaining an acceptable RH either by the running AC or a dehumidifier. Your installer is responsible for leaving adequate expansion space.

Jerry-T. I am not so concerned about the cupping as I am about the buckling.

Is the cupping caused by the moisture and the buckling by the lack of expansion space?

cass62- I do not know what the humidity level was in the house- I will say there was only one day where I felt "sticky", the house is 2x6 construction and maintains a temperature that we feel is comfortable without an A/C...however I think now I will run one for at least a couple hours a day to remove moisture in the air.

Is 70% RH acceptable for a basement? Is 50% RH acceptable mor the main floor?

One more thing- I reread my original post...and I shouldn't have said "severely" cupping. I actually didn't even notice that they were cupping until the installer mentioned it. I would classify it as "slightly" cupping- unless the light is hitting them at the right angle, it's not that obvious. However, the buckling and heaving is very obvious!

I'm seeing 2 issues here.

Yes, the basement is real high in humidity, and will cause the underside of the substrate to have a higher moisture content then the flooring, causing cupping. Your floor guy should have know this, as it is a very common and known problem.

Second, is the fact the wood was acclimated and installed during the winter, and the heating season, when running the heat in the home, has lowered the humidity. How much??? The wood was installed at that low moisture content, and now that the humidity has risen, so has the moisture content of the wood, swelling it, and causing a buckled floor and not just cupped.

But you said everything was fine, till summer. This leads me to believe no control gaps were left in the dry floor to accomidate the swell that was going to happen and now has happened(species shrink & swell coffecient). Edge crush from a swelling floor will have a cupped appearence.

I see both rearing their ugly heads at the same time.

Thanks floorguy. The only room where I see NO issues whatsoever (cupping or buckling) is in my small office where the expansion gap left was almost an inch. This is why I believe the floor guy is at fault, and I can use this room as an example.

He told me something like "the buckling is happening inthe middle because the floors have no where to go- the wall gap is irrelevant". I smell something fishy.

when I was with Bruce they showed us a picture of a gym floor that literally buckled and you could walk under it. Wood expands width wise not length wise so if there is no gaps left width wise that is most likely your problem

You can't compare a house to a gym floor. It is quite possible for a floor to move... and see the effects out in the field first. It depends on what the substrate is, how well it was fastened down and the width of the room. The boards want to move and have no where to go but up on the edges, slight cupping, compression set. It can also start to buckle out in the field without taking up all of the allowed expansion space.

I would like to see some photos before I place "all" the blame on the installer. Homeowners have an obligation too for maintaining a proper environment for wood flooring.

FOLLOW UP:
Floor guy came by, saw floors - said "OH MY GOD". He believes the floors are defective and it is not our fault. When he saw them the first time it was well over a month ago, when they were slightly cupped but not buckled. He is going to call manufacturer and see if there is an issue with the lot the floors came from (luckily we still had one box!). If it is not defective floors, then he is just going to have to relay them...

LOL!!!!

I'll bet money, that there is nothing wrong with the flooring, that would cause buckling.

It is wood and it is doing what wood does. It swells with a gain of moisture content, which your has, and it shrinks with a loss of moisture content. The floor has gained moisture since it was installed... FACT

The floor was installed drier, and now it is wetter.

floorguy- that is my thought. I think it was a faulty installation. I am just glad he is going to fix them.

I just had a premonition. Your floor guy is going to lay new wood for you. Then in February you'll be posting about huge gaps all over. Not that the installer didn't screw up, but you also really need to get your humidity under control and/or consider using an engineered wood.

I install wood floors from time to time and one thing that strikes me in this post was there was no mention of a proper vapor barrier such as felt paper installed under the wood floor and on top of the sub floor.Humidity is going to rise from the basement regardless of what you do if you dont use felt paper under the flooring no matter how long you acclimate the wood prior to installation or how you adjust the humidty in the home your going to have a problem. Check with your installer alot of them know how to put wood together but dont know the right way to do it. One other thing that should be done if the floor runs width wise more than 20 feet it should be run in both directions from the middle by using spline. Also a 3/4 gap is prefferd on all the walls where the floor meets.I would personally not blame the home owner in this case.

Good point of the felt if the flooring was mechanically fastened down . But, saturated felt is only a retarder, not a true moisture barrier.

I hope my own posts are not placing the blame on anyone... too many variables are unknown.

The floor installer is now insisting that it is our problem, and wants an independant third party to come in and inspect the floors. Fine by me. He left 1/4" gap only. There is that pink paper under the floors (Rosin paper?). On one wall only, the floors have expanded all the way to the wall and are starting to buckle at the edge. On the other wall- no movement.

We'll just have to get a third party in here to make an educated decision on the floors.

Smart choice... I would recommend someone certified by the NWFA. Normally certification does not mean much to me... except for inspectors. Anyone can join the NWFA and "claim" to be a consultant/inspector. Only certified inspectors tell you they have taken and "passed" the NWFA training courses.

This is clearly from what is presented a moisture imbalance due to high humidity in the basement migrating upward into the subfloor and hardwood floor. A moisture meter with insulated pins will measure the moisture levels from the top to the bottom of the wood subfloor. If higher from bottom to top a clear indication of high humidity causing this condition. A vapor retarder is only usefull for retarding vapor and when penetrated by all the nails even less helpful for long periods of moisture.
It has been stated she doesn't run the AC so likely a greenhouse effect is also causing high levels of humidity in the upper levels. Find a NWFA Certified Inspector and have him identify what you can do regarding the above.
One can guess, from years of experience, what is causing this but only testing by NWFA standards will conclusively prove what the problem is and how to remediate it.

I commend you NWFACP, you timed that almost perfectly to be 5 years after the last post on this thread, and amazingly enough you did not register yesterday but 3 days ago!

"no mention of a proper vapor barrier such as felt paper installed under the wood floor"

Nothing you can do is going to stop the wood from absorbing moisture and changing size.

It has 24 hours a day, every day, to come to equilibrium with the humidity it is exposed to.

Winter installed floors are not laid all that tight.

Summer floors should be tight.

No fastening is going to stop the movement, n finish is going to stop the movement.

The design of t&G strip flooring is so that only one edge is fastened in place anyway.
The the other edge is free to move as the wood swells and shrinks.
Gaps in the winter heating season, tight in the summer cooling season.
See Chapter 3 of the 'Wood Handbook' linked below.

Figure 3-3 is especially important to understand cupping, and the other changes in shape that occur with changes in moisture content.

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

Hi brickeyee, you wrote that "winter installed floors are not laid all that tight"

Are you saying that professional installers (meaning installers worthy of the word "professional"), would know not to lay the boards tight in the winter and allow for summer expansion?

I'm asking because my kitchen floor is experiencing cupping similar to the original poster's description. I'm in MA, and our kitchen wood floor (3/4" Somerset hardwood, tongue and groove) was installed at the end of January. The wood itself had been sitting in a room adjacent to the kitchen for a month prior to installation. The installers definitely put the boards in tight at that time (I could see that).

Now in the summer, with weeks of humid weather, the floor boards are cupping. No buckling, but I am wondering about the long term consequences, as I simply have no knowledge of this area. The basement is humid at this time of year, but none of the 100 year old floor boards in the other rooms over the basement are cupping. Yes, they do have slight gaps between the boards--that is part of their character. But only the new flooring in the kitchen is cupping.

Should the installers have known not to install the boards so tight together in January? They are local residents of MA, so they know it gets humid in the summer. And (of course) no one asked me whether I wanted the boards to go in tight, and would I have minded if there were gaps to allow for summertime expansion.

Thanks!
Lee

"Are you saying that professional installers (meaning installers worthy of the word "professional"), would know not to lay the boards tight in the winter and allow for summer expansion? "

Yes.

It may not be much since a strip floor has ever single joint to expand over, but even a few thousandths of an inch per strip racks up pretty good over 20-30 strips of wood.

It is sort of the difference between hammering them as tight as you can and just bumping them once.

Hi brickeyee, thanks for responding to my question!

even a few thousandths of an inch per strip racks up pretty good over 20-30 strips of wood.

What a great description -- I never would have thought of it that way until I read your posting. And it makes it so clear.

Thanks again! You are a huge help.
Lee

Lack of expansion joints cut on all sides of engineered flooring at the walls is a major cause of both problems. The picture attached (I hope) shows what I am working on right now. The quarter round and trim board was removed for access to inspect and repair. I have no cupping but there are multiple bucklings of butt joints on the same run of flooring. The ends of the flooring cannot expand outwards with temperature or humididity changes. Notice that some gap was cut and little if any properly cut next to it. Same goes for the the rest of this flooring installation. I would have to think cupping is the same problem - not enough expansion joint cut on the sides of the flooring. Now for the REST OF THE STORY! This type flooring is suppose to float. It is not to be tied to the sub floor in any way. It is supposed to have a vapor barrier pad. none of the flooring should be glued or nailed together or anyway whatsoever nailed to the sub floor, wall or anywhere else.
The installer of my floor child problem used a long brad gun to install quarter round but, shot brads through the flooring into the sub floor - thus locking the flooring in place and guaranteed buckling. The quarter round should have been nailed horizontally to the trim board. You may be able to zoom in on flooring pix and see nail holes. I have to locate any that may be broken off and remove them. One missed brad can can cause a later nightmare. Get them gone now. LOL and next time - do it correctly.