Bathroom Remodel

[Pappy]

Hello everyone - this is my first post. I am installing a custom shower and using Hardie Backer Board over a rubber liner. The liner extends over a shower seat - that will be exposed to direct water flow. I have sloped the 3/4 plywood and covered it with rubber shower pan. What is the best way for me to attach the backer board to the rubber pan? I am concerned about using screws, as I don't want any leaks. I plan on putting a piece of granite over the Hardie Backer board.

[Unquestionably Confused]

Never done this sort of install but...

Were I you, I would first seal the seams/edges of the rubber pan affixed to the ply with silicone adhesive/sealant. Next, when you fit the Hardie board, pre-drill the backer board, set in place, and then "prick" the rubber to mark your holes. Put a quarter dollar sized dollop of silicone at the prick marks and lay the Hardie in place. Place another dollop of silicone over the holes and screw it down.

If THAT leaks through... sell the house for you have been doomed by the fates

Seriously, I'm thinking we're both going way overboard on this. Seamless rubber membrane, properly installed, covered by Hardie board and then with thin set, and granite. Depending on the size of the granite pieces and quality/composition of the grout, location of the screws, etc. it seems like it will be pretty resistive to water migrating in.