Clean your floor with the product recommended by the manufacturer of the finish. We used Bona Traffic for our refinish and I use Bona's product. I used 'whatever' on the floor when it was new and I think it lead to premature failure of the finish. If you have issues with your floor finish and have used the manufacturer's products, then that is one less thing they can push back on you. Bona's products are available at many stores. I buy the largest size and refill the spray bottle.

Our experience has been that the wider the floor planks, the more expansion becomes an issue. With 4'' hardwood at our lake house, we had major issues in the opposite direction (inadequate spacing between boards which led to humping up in a few areas and baseboards being pushed it by expansion). We fixed the problem by removing all baseboards and cutting them back so the floor could expand under them rather than push on them. How big a continuous run of hardwood did you do? And I assume the flooring contractor stored the hardwoods indoors for a substantial period of time to acclimatize them before installing? That's a lot of movement. Fortunately for us we finished our hardwoods with Waterlox, so there was no breakdown of the finish between boards, but I wonder if poly will be vulnerable to large amounts of movement.

As for care, second the Bona cleaner suggestion.

Thanks clinresga,
Yes, the flooring was acclimated in our house for over a month. Our temps have been unusually warm with very low humidity (7%) for awhile and I am sure that has been part of the problem. I think GC has decided to put a soft fill between the extreme areas and bring in humidifiers to see if it will expand back out. Unfortunately that pushes us out by 3 more weeks(due to scheduling issues) when we were supposed to be moving back in today. We have decided that it is best to do everything we can possibly do before moving the furniture back in. Big bummer, but after the week we have had here I am just so thankful and fortunate that my house is still standing.

We have decided on 4" site finished white oak. Our flooring people and our builder weren't so thrilled with our decision to go over 3.25" because of the cupping/capping and cracks you and clinregsa are talking about. They advised us to upgrade our HVAC system so the we have a whole house humidifier. We live in Ohio so extreme moisture or dryness isn't usually a problem, but with the amount of money we're sinking into these floors we decided the furnace upgrade was worth it. Also easier since we are doing a new build. Do you have a whole house humidifier? Can you add one? I wasn't sold on them for our current house, but our new house will have the hardwood floors and a grand piano to worry about.

The flooring people told us they would give us very specific care instructions.

Mom23Es, we have a humidifier on our furnace but maybe that is not enough. Our furnace is new so hopefully there is something we can add that will be more beneficial. Do yo have any specific recommendations? I think I will call our AC/Heat company tomorrow and see what they can suggest. We have a grand piano also that has been in storage while we remodel so that would be a good idea too to protect it too.
Thanks again!

Mom23Es, we have a humidifier on our furnace but maybe that is not enough. Our furnace is new so hopefully there is something we can add that will be more beneficial. Do yo have any specific recommendations? I think I will call our AC/Heat company tomorrow and see what they can suggest. We have a grand piano also that has been in storage while we remodel so that would be a good idea too to protect it too.
Thanks again!