An engineered wood T&G floating floor was installed in basement 90 days ago. We dont have water leakage in the room, but a 3" length in one area and also a smaller area bubbled up, about 1 inch vertical in the worst places. This occurred about July 1. I think it started getting humid here ( > boston) -- maybe my imagination. But its been bubbled about 4 weeks.

So today I guessed where the floor was pressing against a wall and chiseled out a 1/8th inch x 2 inch section of floor - doesn't look like anything improved.

So I guess the question is... how do you pinpoint the problem area, and is expansion the only possible cause?

You will have to pull off all the moldings.

I'm from Boston maybe I can take a look. What town are you in?