Hi. I just bought a old home. I took a shower and found that water leaks in the basement from the shower. It is not the drain. It has actually started to rot the floor. Where should I start. The shower is on the main floor. It is a small one person shower with the small tiles. And a shower door. Should I start with breaking out the tile and replacing the pan?

Thank you,

That would be a start but from what you tell us the framing will need some replacement. The origins of the leak could be a failed pan and grout, drain pipe or even a leaky mixing valve. Start by shutting off the water to this shower and determine which the leak started, this must be done before you can begin to rebuild.