When we bought my house 6 month ago we installed floor at the same time. It was fine for the first 3 months but after that one area in the 1st floor wood start rise. Whenever i walk around it, it sunks an inch as if there is air bubble there. I talked to the contractor who installed it and they did moisture reading and it was around 6~8% around the spot where the floor is lifted up a little bit. There is bathroom right next to the area so we did reading there too and this time one wall had reading of about 12%. I hired a plumber to take out the toilet and see if there is any leak. The plumber didn't want to take out toilet first and instead we went to the crawl space and there was no sign of water leak. We looked behind insulation.
My floor contractor want us to hire plumber again and actually take out toilet because there can be very small leak like a few drops of water every hour that can somehow damage floor.
Should i hire plumber again? Is there another way to find out where the problem is?
The floor was installed in the summer (July) and the floor started lifting in October. Humidity is usually higher in the summer and lower in the winter so i am not sure why this is happening.
We didn't spill any water on the floor and there is no water leak as far as we know.