Hey! It's been awhile! The last time I logged in here was probably 7 years ago when I was installing a floor in my old house. It turned out awesome thanks to the advice of many on this forum.

I've since moved, twice. The house I'm in now has a 20 year old maple floor with no moisture barrier under it. There is close to 2000 sq ft of maple on the main floor, and it's not in awesome shape. Mostly, it just needs refinishing due to dogs and kids over the years. However, it's buckling in a couple of places. It runs parallel to the hallway, and it's raised in the middle of the hallway all the way down, and it's also raised in one of the rooms. The strange thing is, I would expect this problem to subside a bit in the winter when the air is super dry, and get worse in the summer. Well, it's doing the opposite. Humidity in the winter in here is about 26-30%, and the buckling is about twice as bad in the winter. During the summer, humidity is 50-60%, and the buckling subsides a bit and isn't nearly as bad.

This does not seem normal to me. So:

1. What is going on here?
2. What's the best way to fix besides ripping up the whole floor and installing some Aquabar B? My thought was to cut the boards narrower that are at the top of the buckle so they will sit flat, fill in any gaps with some Woodwise, and refinish. I realize that w/o a moisture barrier, I'm going to have some issues down the road again.

I'll do another post with specific finishing questions in the finishing board. I don't know what's changed over the past 7 years, so my plans may no longer be the best plans.

Without a good pin-type wood moisture meter, it is hard to say what is going on.

Without moisture tests to see where the wood is in moisture balance, I cannot recommend a correction.

I suspect its structural

If it were structural, the subfloor would be buckling also, and it's not. I drilled a hole through the wood floor, and it's raised from the subfloor, there's a gap.

It's raised above the original subfloor and the original subfloor is wood? Thats unusual.

Yep, original subfloor is 3/4" plywood. The staples must be pulling out as it buckles.

Use strong earth magnets and see what the fastening schedule is like in the area that buckled, compared to the areas that are firm.

Oh Ok, I get it. I thought you meant it was a sleeper floor. lol