I saw a lot of cupping issues this summer, and I am seeing lots of gaps this winter, but I don't often see cupping with gaps. This house had them: cupping to 0.060" with gaps to 0.075" in some squeaky 5" oak flooring.
I was hired by the OSB manufacturer. The installer said he didn't do anything wrong. The builder said she didn't do anything wrong. It must be something that neither of them are responsible for… Must be bad OSB.
When it's a subfloor issue and/or noise issue, I usually end up cutting open the floor. In this case, the builder was going to pull up the flooring anyway, so I packed up the car with Skil saw, extension cord, broom, dust pan, goggles, ear muffs and all my other inspection toys. Then we got 2 inches of snow. So I have to move everything to the big 4-wd dually just to get up the 5½ miles of mountain road to the highway. The rest of the four-hour trip was fine, with no snow and 50 degrees. (Side note to Mike in NH: Eat your heart out.) So I've either got to get a car to handle the snowy mountain roads, or shuttle my car to the highway ahead of these snowstorms.
The builder cut a couple boards loose in a closet to show me how loose the fasteners were in the OSB. And they weren't very loose. So we decided to cut a more central spot where the squeaks were worse. By now the builder's battery-powered saw was dead, so I got out my Skil saw and extension cord. (See, it pays to be prepared.) She started cutting with it and stopped to say, "At least I don't have to worry about dulling your blade." Well, even carbide blades don't last too long when you cut through fasteners, but I will have to remember to pack a spare blade from now on. And it wasn't dull enough to smoke up the house.
I got my samples, got my measurements, got my photos, saw what I needed to see and headed home for analysis and testing of the samples. On the way home, I stopped by a Verizon store and spent my profits and more on an iPhone for my son for his birthday. Boy, are they proud of those phones.
