I want to install a low shower curb. Why is it that every "pro" uses 4"+ for a curb height? I would like to minimize the step over and use a 2 x 4 set flat on the floor. then the built up height would be 2" or so. Why not? The door has a sweep, water is not directed at the bottom. I have tile os so not worried so much about wet floor. I do not have enough drain pipe depth to allow a no curb.