I just installed a steel tub, put HardieBoard up, mudded the joints, and now I'm ready to tile. Here's my question: since the tub slopes, on each of the sidewalls, on the high side I am 1/8" off the tub with the Hardie Board (level)on one end, and around 1" on the other end. On the 1" end, I am 1/4" above the tub flange. Since I need my tile to be level as well, am I supposed to fill that whole 1" gap with silicone?!
Your tile will need to be the same distance from the tub all the way around and also level. What this translates into is your first round of tile will be all different sizes -- each one cut to fit. This is a pain in the !#$@, but there isn't another way. Start at the lowest point of the tub when you start the first round of tile or you'll be sorry
Sounds like you have too big a gap between the low end of the tub and the hardibacker. What you should do is pull the hardibacker and cut a piece that will cover the flange What I would do (keep in mind that I'm a DIYer) is put a wedge of hardibacker in with construction adhesive and a screw (in the 1/4" that will be above the flange). Then tape and mortar and you'll be ready to go. You don't want the tile to be unsupported by hardibacker any more that necessary.