Hi I am in the process of repairing a stall shower where originally, ceramic tile was installed on water resistant sheetrock.The shower has a fiberglass base which I am going to leave in place.Due to leaks in the bottom part of the shower wall just above the shower base,the sheetrock behind the tiles rotted and disintegrated and needs to be replaced. I am considering replacing the bottom two feet of damaged sheetrock with new ceramic tiles installed on hardie backer board.If what I read is correct I should set the hardie backerboard 1/4 inch above the top of the shower base flange and put some form of waterproof barrior in back of the hardie board. If the above is correct my questions are as follows:
1)should the waterproof barrior material overlap the shower base flange in any way or should it just be cut off at the end of the hardie board?
2)which should I apply between the gap created between the shower base top of flange and where hardie board meet, mastic or silicon.?
3)when I bridge the bottom ceramic tile across the gap beteen the hardie board edge and top surface of shower base flange should I continue with the mastic cement holding the top portion of the tile against the hardie board to the part of the tile where it presses against the inside of the fiberglass base or should I silicone that half? I know you have to leave a small gap of maybe 1/8 inch between the fiberglass base and bottom edge of tile for application of the silicone.
Any help would be much appreciated jim