My cast iron tub creaks when full of hot water and I am sitting in it. I am cont

I am concerned it wasn't installed properly or with sufficient support and will fall thru the floor with me in it! It doesn't appear to be dropping from its placement against the walls surrounding it. Is it a natural reaction for the cast iron to creak when filled with hot water? Taking a bath should be relaxing. The noises concern me and it's hard to relax. Any experience with this situation or suggestions would be appreciated.