Fixtures, Fixture Fittings, and Appliances
Fixture Requirements
Fixtures must be of an approved type, smooth, impervious, and free of concealed fouling surfaces. Know the required clearances: water closets need side and front clearance to walls and partitions, lavatories and sinks need specified spacing, and fixtures must be accessible for cleaning. Floor drains, drinking fountains, and hose bibbs have specific requirements. Fixture fittings include faucets, valves, and supply stops, and they must be listed and installed per manufacturer instructions.
Traps and Connections
Every fixture must be individually trapped and vented unless an exception applies. Fixture drains must be the size specified for the fixture; a water closet typically requires a larger drain than a lavatory. Indirect waste connections protect potable water: refrigerators, ice makers, dishwashers with certain configurations, and food preparation sinks may require an air gap or air break. Know the difference: an air gap is a physical separation; an air break is a discharge into a receptor below the flood-level rim.
Traps in Questions
Common errors: assuming a dishwasher may discharge directly into a sink trap; ignoring that a clothes washer requires a standpipe with a trap and vent; and forgetting that a fixture with a flushometer valve needs higher minimum supply pressure and a larger supply pipe than a tank-type fixture. Questions also test that fixture outlets must be protected and that a fixture may not be installed in a location without adequate access.
Worked Example
For a public restroom, count the required fixtures using the occupant load and the code's fixture ratio table. If the ratio is one lavatory per 40 occupants and the load is 120, you need three lavatories minimum; then verify spacing and clearance requirements before finalizing the layout.