Plumbing and Mechanical Requirements

 Plumbing and Mechanical Requirements

While most codes that were previously discussed within our book, The Codes Guidebook for Interiors, were utilized for the safety of the occupants within a building, the plumbing and mechanical requirements focus on addressing health and welfare concerns. This makes it critical for us as designers to know how to determine the quantity of plumbing fixtures needed in a project and how a design affects the differing components of a mechanical system.

How to Determine the Quantity of Fixtures

It is critical that the number of plumbing fixtures required is established in the early stages of a project. The number of fixtures is determined by the plumbing code which indicates water closets, lavatories, bathtubs and showers, drinking fountains, and other fixtures. Usually, each floor is required to have at least on toilet, but the actual number depends on the type of occupancy and the occupant load of the building. Within the IPC, Table 403.1 “Minimum Number of Required Plumbing Fixtures” aids in calculating the exact number and type of plumbing fixtures. Note that it is always best to round up to the nearest whole number when face with a fraction or decimal.

IPC/IBC Table 403.1 - Assembly Load

Essentially, the calculation is a series of division, starting with the number of occupants in the building. This number is then divided by two, or split in half, to represent male and female occupants. Let’s say that the occupant load of a new school was 1000 and when divide into males and females it is 500 each gender. Taking this number and Table 403.1, we can see that for the Educational (E) occupancy section the number of water closets for every 50 people is 1. This means that for every 50 people within the building, one toilet is required, so after taking our 500 and dividing it by 50, the minimum number of water closets (toilets) required is 10 for males and 10 for females.

Components of a Mechanical System

Three Types of Heating and Cooling Loads

A mechanical system is a system that provides ventilation, improves air quality, and regulates the interior temperature of a building, otherwise known as an HVAC system.  Although typically calculated by the engineer, heating and cooling loads are how much energy is required to heat and cool a space in order to maintain a comfortable environment. When it comes to designing the size and type of mechanical system, the cooling load is the primary factor – along with the heating load - because these are largely dependent on the size of the space and how many people will occupy it, as well as what activities will take place.

The codes also require an exhaust system in certain rooms and occupancies. Exhaust refers to air being removed from a building or space, including smoke, germs, odors, chemicals, etc. Proper exhaust and air quality is crucial in hazardous types of occupancies specifically, so the codes require a great deal of rooms and areas to be exhausted. When exhausting area, an exhaust fan is connected to a pop or duct, drawing the air out to the exterior. On the other hand, ventilation takes air from the outside and brings it into a space to dilute harmful elements and odors. This can be through natural air flow, like opening a window, or by a mechanical system known as mechanical ventilation. The codes regulate both by setting the necessary amount of outside air based off the floor area of a space and the estimated maximum occupant load.

Conclusion

As previously mentioned, most codes are written and regulated for the safety of the occupants within a building. However, the plumbing and mechanical requirements focus on addressing health and welfare concerns. For designers, it is just as important that we know how to determine the quantity of plumbing fixtures needed in a project and how a design affects the differing components of a mechanical system.