A 4 inch building drain installed with a slope of 1/8 inch per foot will result in _____.

In plumbing design, the slope of a building drain plays a crucial role in ensuring proper drainage and the effective flow of wastewater. A 4-inch building drain installed with a slope of 1/8 inch per foot can negatively impact the fixture unit loading allowance. Fixture unit loading refers to the amount of drainage capacity needed to accommodate the expected wastewater flow from plumbing fixtures.

When a drain has an insufficient slope, as might be the case with a very shallow slope like 1/8 inch per foot, it can lead to slower drainage. This slow drainage can cause problems like water pooling or stagnating, which can affect the overall system's functionality. Therefore, in this scenario, the reduced capacity to handle the expected flow translates to a lower allowance for fixture unit loading, as the system may not adequately handle the volume or flow rate from the connected fixtures.

Essentially, the 1/8 inch per foot slope may indeed lead to a reduced ability to support the expected loads from the fixtures serviced by the building drain, indicating insufficient drainage capacity for the anticipated fixture unit loading. This can inhibit the proper discharge of wastewater and necessitate a reevaluation of the drainage design to optimize performance and compliance with plumbing standards.