A 90-degree bend is a quarter turn around a circle. A full circle is 360 degrees, so 90 degrees is 90/360 = 1/4 of the circle. That’s why the correct fraction is 1/4. To put it in context, a 180-degree bend would be half a circle (1/2), 45-degree would be 1/8 of the circle, and 22.5-degree would be 1/16 of the circle.

Vent terminals must rise above the roof surface enough to stay clear of weather, snow, and debris so sewer gases can vent freely. The minimum height specified is 12 inches. This ensures the vent remains exposed above potential snow cover and rain runoff, reducing the chance of blockage or water intrusion into the vent opening. Heights like 6 inches can be overwhelmed by snow or wind-driven rain in many climates, while 18 or 24 inches go beyond the minimum without providing additional practical benefit for typical residential installations.

Understanding how a bidet receives water helps you see why mixing multiple supply configurations on one fixture isn’t allowed. A bidet should have a single, safe water setup: either hot and cold are provided so you can mix to a comfortable temperature, or a tempered water supply (usually via a tempering valve) is used, possibly with a cold line. The important point is that you don’t feed the fixture with more than one independent water configuration at the same time. The option that combines both hot and cold with tempered and cold would require two separate, active supply configurations to the same fixture, which creates backflow risk and confusion in operation. That’s why it’s not acceptable. The other configurations—hot and cold, tempered and cold, or tempered only—are valid because they represent a single, coherent way to supply the bidet’s water with safe temperature control.

Drainage Fixture Units measure the expected wastewater load a fixture places on the drainage system, guiding how large the piping must be. For a water closet, the code table used in this context assigns 4 DFU, reflecting the relatively high discharge involved with a toilet flush, especially for flushometer-valve style toilets common in commercial settings. This higher value ensures the waste line is sized to handle peak flow without siphon or backing up. While some tables may list smaller DFU values for other toilet types (like gravity-feed models), the standard for this material is 4 DFU for a water closet. When sizing a project, you would add 4 DFU for each water closet and combine with DFUs from other fixtures to determine total demand on a branch or stack, then apply any applicable demand factors.