I have recently installed solid Hickory pre finished flooring by Somerset. I checked the moisture levels in the flooring and in the sub floor prior to installation, the Hickory was at 6% and the sub floor was at 8%. It was with in the acceptable range. I have gutters around my entire house with no drainage issues. The crawl space is dry and well vented. I used aqubar paper under the hickory as recommended by the flooring rep. I installed this flooring in my entire house, upstairs and down. It has been 6 months since the install and the entire floor is cupping and swelling. I left at least a 1/2" expansion at all walls and doorways. I live about a mile from the ocean in San Diego and the area is humid but a pre finished flooring shouldn't do this. What do I do?

Hickory tends to move around alot!
Did you install with cleats or staples? Sometimes I think staples hold a little too well and can lead to cupping.
What was the weather like during the acclimatization? Did you run any air conditioning?

Try a dehumidifier. It might just cure the problem. If it gets worse, get a humidifier. This has been the worst year I have seen as far as humidity and temps go.

I would imagine things have changed since the time of install to cause the movement. Solid hickory over a crawl space can be difficult to maintain. Here is what normally happens, hot humid air is drawn into the crawlspace through the vents. the air in the crawl is cooler than outside and viola you have condensation. water vapor is the most pervious form of moisture. Moisture is sucked into the subfloor then into the finished floor because its drier. wood is hygroscopic and will take on and or elevate moisture until it meets an equilibrium within it's environment. Get a meter take readings above the floor and below that will tell you where the dehumidifier needs to go.