HI - brand new to the site. I have an approximately 38 year old house in south Florida. My walk-in shower in my master bath is leaking. It is tiled and was obviously built to fit - it is an odd size and the drain is not in the center. I have cut into a wall that lets me see the method of construction and it appears it was built within a 1'x8" wood box and they used some sort of paper - looks likes roofing felt. My question is : would it be easier to try and rebuild it using a vinyl liner or move the drain ( it is in concrete ) and try to adapt a ready-made size shower pan ? Thanks for any input.