The cast iron shower base is the vinyl cover that is installed in the ground before laying the floor. The indoor shower creates a water resistant barrier to protect all types of ground, such as wood or concrete, to prevent these materials absorb water. Place the base of vinyl as extended and smooth as possible on the surface of the floor and around the drain of iron. Try to center the hole under the base and make sure it covers the entire floor where the tile or other material will be installed.
Stand on the cover to hold it in place and move your hand across the surface, pressing it against the floor to smooth edges and folds. Once the cover is completely smooth, paste the edges on the floor or wall using tape to hold the cover in place of cast iron shower base.
Place the cast iron shower base drain below deck by pressing gently on it until you feel the opening. Cutting the cover continues to leave the exposed drain, but leaving 1/8 inch inward of the hole cover. Place waterproof sealant around the edges of the hole and under the shower base, slightly raising the cover and using the knife to apply the sealant.