How to seal below concrete board sealed with RedGard
I am remodeling my bathroom. I will be installing ceramic tiles in the shower stall walls, and using an Onyx shower base. I have already installed concrete board (HardiBacker) onto the studs, and plan to waterproof it with RedGard.
My question is this: since there is a 1/4" gap between the bottom of the concrete board and the lip of the shower pan, what should be done to waterproof that gap? I understand that there will be mortar there in back of the overhanging tiles, but I am concerned about water getting through the tiles and mortar.
Any advice is appreciated!