What inessential characteristics of laundry trays are not allowed in construction?

Unsmooth surfaces in laundry trays can lead to issues related to hygiene and maintenance. Such surfaces can harbor dirt, bacteria, and grime, making it difficult to clean properly. In construction, it is essential that surfaces associated with plumbing fixtures are smooth to ensure easy cleaning and sanitation. Smooth surfaces also contribute to the durability and longevity of the fixtures, as they minimize areas where moisture can accumulate and lead to deterioration or mold growth. Standards for plumbing installations prioritize not only functionality but also safety and hygiene, which is why unsmooth surfaces are deemed inessential and not allowed.

The other characteristics, while they may be factors in evaluating laundry trays, do not have the same direct impact on cleanliness and hygiene, which makes unsmooth surfaces a more critical aspect of construction standards.