Abadi 
ADA vs. ANSI Water Closets
Posted on - Tuesday, February 2nd, 2010The ADAAG has figure 28 which shows you the three layouts you can use for a water closet not located in a stall
Depending on the direction of travel this Figure guides you in the amount of clear floor space required at the water closet and the location of an adjacent lavatory.
ANSI, on the other hand, only has one way that they allow it. Figure 604.3. This figure describes not only the clear floor space required, but also that a fixture may not overlap the space.
When designing in a municipality that requires the use of IBC and ANSI, make sure you don’t design per ADAAG, or you would miss this one.