The wall around a tub should have a moisture barrier that overlaps the lip of the tub. I would bet that 99.9% of builders skip this step. Then they put up hardibacker, great stuff but somewhat pointless since they don't TAPE THE CORNERS.  Now if done right and water somehow gets behind the tile, it will flow back into the tub instead of rotting your studs. NO GROUT should be used in the corners or where the tub meets the tile. These areas are subject to movement and should be caulked.  What happens when your corners slowly leak....


Start asking builders if they use a moisture barrier and if they tape the corners and seams on the tile backer board.  I bet this isn't a commmon complaint because it takes years to show up and most people don't stay in their homes that long.  This is a major repair that should never have to be done. How much money are you guys saving on a little tape and tar paper?