By Richard Grace
(original publish date: May 19, 2016)
Virginia Plumbing Code Section 403.1 dictates the minimum number of plumbing fixtures in a space based on its occupancy (function) and occupant load (maximum number of people). The building code requires the occupant load of the space to be calculated using its entire square footage, thus the number of required plumbing fixtures reflects the greatest possible occupant load. This is called simultaneous use.
However, there are some occupancies where the people may move from one area to another, but never fill the entire space at once. This is called non-simultaneous use, and it is most often seen in schools, Group E. Children are rarely in a classroom and auditorium at the same time, so why should unnecessary plumbing fixtures be required? Rooms such as the auditorium and gymnasium are generally for after-school activities rather than simultaneously used during school hours.
Unfortunately the code does not recognize this concept; however, Fairfax County will permit non-simultaneous use in Group E only. To determine the required number of fixtures, use the larger occupant load calculated from the following room combinations:
- Classrooms and administrative rooms used simultaneously during the school day.
- Auditorium, gymnasium, cafeteria and other similar rooms that could be used for after-school activities.
This is a reasonable approach that maintains the spirit and intent of the plumbing code while reducing the costs related to potential redundant fixtures.
Non-simultaneous use is permitted only with the permission of the Fairfax County Building Official through the code modification process. Learn more about code modifications and submission requirements.