Hello. The builder put final coat of polyurethane on our 3 1/4" oak floor last week, then cranked up the electricity in the house for the first time, putting on the air conditioning. The floors have cupped, just like the illustration in your article, "Cupped Hardwood Floors. Why?"

There have been no attempts by the builder to equalize the humidity, they are just telling us it will settle down after a couple of months. There is about a two to three foot crawl space under the house. Not sure if a vapor barrier was put down. The flooring was acclimated to the house, but at outdoor temps, as the electricity was not on.

What remedial action should the builder be taking, and should we close on this house on Friday, with the expectation that the floor is going to eventually equalize and lay flat?

Thanks,
Lisa Ponder

The floor may or may not return to normal. If you want to close the transaction, perhaps consider having an agreement added to the closing docs that says the builder fully warranties the flooring to return to perfectly flat with no gaps between the boards. If it does not by a certain time period, the builder will pay 100% of the cost to move all your belongings, repair or replace the floor properly, continue to warranty the repaired floor and pay for you to live elsewhere while the floor is being repaired. The builder will balk at this with some bogus mumbo jumbo about how great a reputation he has, that he "stands behind" his homes ( whatever that means ) and stuff like that. Don't fall for the baloney. Get it in writing. Have a real estate attorney write it up and have the builder pay for the attorney's fees. IMO, that is the only way I would agree to close escrow on the home.

Dear Gary,
Thank you so much! We were afraid we were going to have to play hard ball with them, and you have confirmed it. They are currently acting like cupping is a normal process in laying a hardwood floor. What do you think is a reasonable amount of time for the floor to return to flat?

Thanks again,
Lisa Ponder

Cupping is not normal, if things are done right and the protocol for before, during and after are not met, your going to have problems. Cupping being one of them.

Sanding a cupped floor flat, is not the answer, either!!! That is the first thing, that he is going to want to attempt, when the cupping doesn't go away.

So what IS the answer?

At this point, I would only do one of two things....either take Gary's advice and get the guarantee and acceptable future resolution in writing, or have them tear out and reinstall the floors prior to closing. The bottom line is, the flooring never should have been installed until HVAC was up and running at normal living conditions and the flooring was acclimated. Even if the floor does flatten out eventually, you're likely to be left with gaps and squeaks.

I agree cupping is not normal and a properly installed floor should not be cupped. However, one remedy recommended by NOFMA is to sand a cupped floor ONLY AFTER IT HAS BEEN THOROUGHLY DRIED and all sources of moisture and the cause for cupping have been resolved. While this is not ideal, it is done all the time and done successfully. The key is to allow the flooring and subfloor to dry completely.

Thanks for that clarification on sanding. I have 2 followup questions.

1. what material should be used between the sub floor and the hardwood floor during installation and is this in addition to the vapor barrier installed in the crawl space?
2. is it ALWAYS wrong to install hardwood before HVAC is up and running?
Lisa Ponder

1) Typically, most wood floor manufacturers recommend 15 lb. asphalt saturated felt paper be used between the subfloor and the wood floor IF the wood floor is a 3/4" solid. There are other products for different applications. An alternative is Fortifiber Aquabar-B or their HD-15.

2) Usually. The flooring MUST be acclimated/equalized to the NORMAL, LIVED IN INTERIOR temp and humidity. That is typically 65 to 75 degrees F and 40 to 60 percent relative humidity. The HVAC system will usually provide this when it's on and operating. In SOME locations, it may not be needed but that would be rare. Also, if it is late spring and the measuring instruments ( hygrometer, thermometer and moisture meter ) confirm that the interior levels are at normal living parameters at all times, then running the HVAC may not be needed.

The reason many builders do not do this ( run the HVAC ) is:

1) they do not want to pay for the cost
2) they cannot get the local power company to hook-up the power in time.
3) they cannot get the local municipality to give them a permit to do so.
4) they do not understand the science involved in building a home

Hello, I am the flooring distributor in this dispute. I believe the prospective buyer Mrs. Ponder has now backed out of the contract but would appreciate your opinion after I give you some more infomation. Indoor temp 74 degrees F, humidity 50 percent. I use a delmhorst meter and plunger with 1.5 inch insulated pins. Here are the readings from 3 different locations and 5 readings each location in this order: just under surface, 1/3rd through flooring, 2/3 through, just in subfloor and all the way down. 1st 7.0,7.9,9.4,11.8,13.6 second 8.5,8.7,9.1,10.9,13.0 final 8.5,9.4,9.2,10.5,12.1. I also measured the total width of 10 boards in 2 places with results of 32 and 25/48 on one and 32 and 26/48 in the other. The floor was sanded around May 26th, the HVAC has been running about a week (I KNOW,I KNOW) Not the way it is supposed to be done but in Charlotte NC it is next to impossible to get temp earlier. While I am not a certified flooring inspector I do have an open mind and 15 years experience.
We all know the first 5 do not count and by the way I do employ a certified NWFA inspector whom I did verify my ideas and thoughts with. This floor in my opinion needs time and time only. It will lose another 1+ % moisture content amd be totally flat by mid winter AT The very latest with no separation. Although this floor is mildly cupped we know sanding now is not good. If the floor was ripped up and installed the "correct way" there is a small chance the floor would expand and cup next summer. I would argue that this current floor is a "known" It is unsightly and I hate! cupped floors but this is temporary. I will e-mail you photos if I can find your e-mail. Thoughts appreciated Brad Knight-President Knight Hardwood Flooring, Inc Indian Trail, NC Brad@KnightHardwood.com

Probably shoulda run the HVAC a little at a time. Top is drier than the bottom so it's naturally going to cup a little. It may rectify itself. However in this high Rh environment right now I don't think it's wise to install and finish without HVAC on.

Sounds like the prospective owner has been doing his homework and is pretty knowledgeable as is the builder.
But builders try and pull that temp thing out here too and it is just an excuse for not paying the electric bill for a couple measley months.

Of course the installer/hardwood contractor should have stepped up tho the plate and said no way. But if your wanting to collect on 30 grand then you do as they say huh? But alas, time frames and schedules are always off on jobs so the finish work I bet shoulda been done maybe a couple months ago when it would not have mattered as much. Am I close?

Was the floor cupped before the HVAC was brought to operation?

Was there a protective application laid over the floor until completion and final punch list completed?

Hi,

I'm not sure if your name is Emmitt or Brad but thanks for responding,

Your MC measurements verify the reason for the cupping. The bottom of the wood has a higher MC than the top. WHY the bottom is higher needs to be determined. Was the subfloor a higher MC because it had been rained on and not sufficiently dried prior to the flooring being installed? Or is there an ongoing moisture problem under the home? I agree the flooring should NOT be sanded at this time. I have seen SOME floors return to normal after they have been fully dried. I have also seen some improve but not return to completely flat. Since both the builder and yourself are confident the flooring will return to perfectly flat without consequence, my suggestion to put it in writing as a separate warranty to the buyer would seem a reasonable course of action.

Hi Gary,

Thanks for all the info. After some drama, we are going to close on the house tomorrow. We would have preferred to wait for results, but we got a 4.25% interest rate that was going to expire so we had to close. Anyway, the builder has agreed to replace the floor. We don't want cupping to happen again, so my builder would like to talk to you if possible. He is still of the opinion that there was nothing wrong with the method of the installation of the floor, and has told me he will do anything I ask to get it right. Even though he thinks my research is a bit flawed on this, which it could be!, he is willing to work with me on getting the floor right.

How do I know what to ask for? It seems to me if he acclimates the wood to HVAC conditions, everything should be fine. I do know it rained a lot in Charlotte when the subfloor was installed. That was over 2 months ago though. What kind of scientific readings should I ask for before the new floor is put in? You got the readings from Emmitt or Brad from the floor. What are your recommendations?

Thanks for everything, Lisa Ponder

Selva Lee Tucker is a Nofma&Nwfa inspector and consultant in your area.
He along with Gary, may be able to set your GC straight. Some are hard headed.

https://www.tucksfloorinspectionservice.com/