I live in Northern Virginia. My builder had Eterna finished solid Maple floors installed on the entire first floor of my new home at the time of construction. Apparently, the moisture level was too high so the floors cupped. We placed industrial dehumidifiers in the basement, added a return in the unfinished base-still cupped. Our builder tore the floors out and replaced them with the same product. One month later, the new floors are cupped. HELP! The builder is agreeing to replace the floors again with a different manufacturer's product at our choice. Great but what should we get? Is this typical of maple or Eterna?

Any advice on what direction to take would be GREATLY appreciated.

Thanks,
Cupped in Virginia

Did you see the replacement floor the day it was installed?

Hi Cupped,
Chuck's question maybe that perhaps the builder never did install new floors and just told you he did; hoping that they would flatten out. Am I right Chuck? I wouldn't think that the brand of flooring or the species would matter in regards to cupping. The flooring does need to be properly stored at the wharehouse or it may pick up excessive moisture; transportation of the materials, along with proper acclimation are also critical. Maple isn't quite as stable as other hardwoods but I've installed lots of prefinished maple floors without incident. Was the basement slab poured after the floors were laid? It may still be releasing a major amount of water vapor. A moisture test of the subfloors is in order. Should be around 10 to 12 %. Anything higher than that indicates a moisture problem. Also, a 15 lb. ashpalt paper vapor retarder should have been laid before the flooring went down, per most manufacterers instructions. I believe what you have is a hastily laid floor that the enviroment wasn't ready for.

Thanks for your quick responses.

The replacement floor was installed 18 months after moving into the house. I watched them tear the old out and install the new. Asphalt paper was used. The basement slab was poured before the original floor was installed. I am running a dehumidifier in the basement which by the way is one big open room with no drywall. We hired a building inspector who found no leaks in the foundation or structure. Half the subfloor is at an acceptable moisture level (7-8%), but the other half is a little high (14%) according to the Eterna Manufacturer's Representative. Even the half of the house that is at an acceptable moisture level, the floors are still cupped just as bad as the floors on the other half of the house.

We had the installer place the open boxes of new wood in our living room for three weeks prior to installation. It was pouring down raining the entire week the new floor was installed. The wood was cut on our front porch. Not sure if this could be a factor??

Any thoughts about changing species? Santos, kampas, Brazillian cherry? Any advise is appreciated.

That 14% is too high. There is moisture coming from somewhere that is causing that 14% reading. After nearly 2 years, your subfloors should read the same unless there is a moisture problem. Also, what is/was the moisture content of the flooring prior to being laid? What was/is the relative humidity level? When I lay a floor, I test the subfloors in various locations and test the flooring also. I set up a humidistat to test relative humidity (should be about 50%+ or-5%). Then if all things test in the normal/acceptable range, I'm ready to install. Switching material to a more stable species is fine but you still need to locate the cause of that 14% reading. You may want to consider an engineered floor. Owen's Plank Floor would be a good choice. There maybe a problem with that Eterna flooring but how come they are not testing prior to it being laid? My point is, if the problem is with the material, then that should be determined prior to installation. I still believe you have an enviromental moisture problem. Floors "cup" for only one reason; excessive moisture on the bottom/back side (the side that is unfinished).

Your roof is leaking into a wall.

I agree with Gary.


He remove one floor off a wet subfloor, and put a new floor in on the same wet subfloor.

I agree with the lack of moisture meters is going to cost this installer or the builder big time!!!

Your basement seems to be the problem. What is the temperature and humidity of the basement?

I bet it is high on the humidity side. Your subfloor is gaining moisture from below. I bet the deeper the probes on the moisture meter penetrated, the more moisture content was present. Maple is a very unstable wood.

There is a 4% rule for Oak flooring, I would make that a 2% with Maple!!!

The flooring must be within 4% of the subfloors moisture content, to even consider installing it. I like it closer to 2% difference, if not right on the money.

The humidity level as of last week when the mill rep. came out was 47% downstairs and 45% upstairs which he said was very acceptable. They probed several places upstairs in the flooring itself and the highest they found was like 9%. Downstairs they probed the subfloor in several places using a slide-hammer type probe they found 2 places that were 12% the rest of the places they tried were 10-11%.

I'll add my two cents based on personal experience but it may not relate. It does, however include Maple. Without knowing any better, a few years back when I was new to the business we had an engineered Maple "grow" after the installation--and this was a gluedown.

I tend to believe the only reason was the conditions during the installation. Eighth floor condo on the beach with rain and windy conditions all week. The cutting took place on the balconey and the doors were pretty much left open all day while we were there, allowing salty gulf water air in.

What is the width of the maple flooring? I'll bet you have a plank floor. Maple plank floors move like crazy. Also, while knowing humidity and temp levels now is ok (helps to see if you still have problems), what matters is what the readings were at the time of installation. Let me pose a scenario. You have the flooring acclimating to a normal (?) enviroment. 45 to 50% relative humidity, temp set at around 72%, HVAC on all the time to maintain temp and humidity, subfloor at around 10%(we already know you had readings of 14%, which indicates a problem) and flooring at around 8%. Now the week of install, it rains cats and dogs and you're cold, so you turn the furance up. Besides, the installers are running in and out letting in that cold air so the furnace is working overtime. Now the relative humidity inside drops to about 30% because of the furnace drying the air out and the flooring is now losing moisture as the installers are nailing it up tight. Your once 8% moisture content of the flooring now drops to around 6% as the installers keep plugging along. Now the install is done and the rain has ceased so you turn off the furnace and the humidity returns to normal, 50%. Well, those 5" maple planks start absorbing the moisture in the air and start expanding abit. As they do so, they exert tremendous pressure against each other and have no where to go but up. Now you have a "cupped floor", not because of subfloor moisture but because relative humidity was not maintained at a constant normal level before, during and after installation. There are so many various factors involved it is difficult to determine the exact cause of your problem. Still, the scernario that I presented MAY have been the contributiong factor.

The boards are 2 1/2" in width. I think you are correct about the doors being open. The humidity levels were fine the days prior to the installation. I can see that the door being open during the rain could make a huge difference.

I sincerely appreciate everyones' advice and input. We are going to go with the mahagony.

Here's a dumb question. Did they leave a good 3/4" gap around the edges under your trim? How wide are your baseboards and do you have quarter round or shoe molding? If the drywall is 3/4" off the sub floor that would give a good 1/2". You can try slipping a thin stiff wire with a small bend on the end under any gaps between the hardwood and your trim. Push the wire under as far as you can and rotate the wire 90 degrees, then try moving it back and forth to determine the clearance.

Cupping is usually a moisture imbalance, but compression cupping is another possibility.
Is there gapping between the strips or are they tight together?
Ray

Here's a picture of our floor that is over 46' in length with zero to about 1/16 in clearance under the baseboards. Any comments or information about compression cupping would be welcomed.

moisture cupping, not compression cupping.