I sawmill kiln dry and build all types of furniture and wood products.
I have a small showroom and store lumber and unfinished flooring in the room.
I kiln dry to 6-8% mc.
The lumber and flooring (all unfinished) will gain moisture after a few months, up to about 10%mc.
The building is heated/ac about half of the yr. Were in N. central TN, and spring and fall we open the windows.
I haven't seen any problems with furniture MC problems like shrinking panels or changes in glue joints, but I'm worried about the flooring not being 6-8% (and it's really hacking me off since I go to great lengths to get a uniform MC throughout the kiln load, and a few months later moisture is back).

Thanks for any advice.
jim
I'd ask at Woodweb kiln drying forum but I'm not welcome because I don't dry 750,000bf or more per yr (I'm a 1 man show).

It is gaining moisture content from the humidity.

Keep it around 30% humidity where your storing it, and it will maintain the 6-8%

It's mainly where you are at. I live east of you and most of the rain we get comes from the west.