Thanks, someone in store told me similar info. He uses thinset to join panels, they are cement based, the pan looks like a diff. cement base material inwhich they glued tile to. the sill has a rubber sheet going past the ends behind the end pieces assuming this is a waterproof device and the sill is made of 2x4s stacked and top filled with a white cement under sill material. I have to reconstruct sill area the tile hsa been leaking to the corner outside wall.