Designing Kitchens and Bathrooms - Concrete Shower pan for tile shower

I have installed CPE in the bottom of a tile shower that I am building and installed the Hardibacker board over it but made the mistake (I believe?) of nailing through the low part of the board (about one inch off floor) and through the CPE (rubber pan) to the studs - which if I understand right destroyed the water holding capacity of the CPE? I am looking to patch over the first 6 inches of CPE on the floor and take it up to about 4 inches on the backerboard to reseal those nail hole and seal the bottom of the backerboard back to waterproof> Any ideas on this or other alternative ways? Have to do this soon so I can get the mud down to cure as House is closing very soon! Thanks.

Go to John Bridge (http://johnbridge.com) , go to the forum. They work through this type of shower all the time. You have done some things they won't like, but they will help you fix it right, and quick!