Bathroom walls must have a nonabsorbent surface to a height of at least how many feet above the floor?

The requirement for bathroom walls to have a nonabsorbent surface up to a height of at least 4 feet above the floor is based on health and safety standards that aim to prevent water and moisture damage, as well as limit the growth of mold and bacteria in areas exposed to water. Bathrooms are particularly susceptible to high humidity and splashes from sinks, tubs, or showers, making it crucial for the wall surface to be resistant to moisture.

Installing nonabsorbent materials such as fiberglass reinforced panels or ceramic tiles to this height helps protect the underlying structures, maintain cleanliness, and promote easier maintenance. This standard serves to enhance sanitation and durability in bathroom spaces, ensuring that building codes are met and the occupants' health is safeguarded.