IRC 702.4.2 states that, “Gypsum board utilized as the base or or backer board for adhesive application of ceramic tile or other nonabsorbent finish material shall conform with ASTM C630 or C1178.”
Anyone know what is in those ASTM standards?
I inspected a home with 4.5 baths and moisture resistant backer board was not used at the tub/shower enclosures.
Do the ASTM standards call for moisture resistant backer in this application?
I understand what common sense dictates but I’m trying to leave common sense out of this for now.