405.4.1 Floor Flanges
Floor flanges for water closets or similar fixtures shall be not less than 0.125 inch (3.2 mm) thick for copper alloy, 0.25 inch (6.4 mm) thick for plastic and 0.25 inch (6.4 mm) thick and not less than a 2-inch (51 mm) caulking depth for cast iron or galvanized malleable iron.
Floor flanges of hard lead shall weigh not less than 1 pound, 9 ounces (0.7 kg) and shall be composed of lead alloy with not less than 7.75-percent antimony by weight. Closet screws and bolts shall be of copper alloy. Flanges shall be secured to the building structure with corrosion-resistant screws or bolts.