Building codes may be adopted by statute or regulation. They may require sex-separation or they may require unisex toilets. New building codes usually do not apply retroactively. Thus, building owners may choose not to update existing features because it allows them to continue following the older building codes that govern those older features. These regulations are mostly based on the precedent created by original legislation. They sometimes also work to eliminate the longer wait time females often face by creating a ratio of more female toilets than male toilets.