A plumber lays out a water closet centerline beside a side wall. What minimum centerline clearance to the side obstruction is commonly checked?
Correct Answer
A) 15 in.
A water closet is commonly laid out with at least 15 in. from the fixture centerline to a side wall, partition, or fixture. Other choices are too tight, recommended comfort clearance, or front clearance.
Why This Is the Correct Answer
A water closet is commonly laid out with at least 15 in. from the fixture centerline to a side wall, partition, or fixture. Other choices are too tight, recommended comfort clearance, or front clearance.
Why the Other Options Are Wrong
Option B: 12 in.
Choice B (12 in.) is rejected because 12 in. is a different published number than the cited Water closet clearance value; Plumbing fixture layout clearances supports 15 in. The cited answer is 15 in.
Option C: 18 in.
In mechanical and plumbing, 18 in. is the wrong selection for Water closet clearance: 18 in. is a different published number than the cited Water closet clearance value; Plumbing fixture layout clearances supports 15 in.
Option D: 21 in.
The trap in D is 21 in. That selection is wrong because 21 in. is a different published number than the cited Water closet clearance value; Plumbing fixture layout clearances supports 15 in.; A water closet needs 15 in.
Memory Technique
Link water closet clearance to its book condition; a different condition means a different answer than 15 in.
Reference Hint
Open Mechanical and Electrical Systems for Construction Managers, 4th Ed., 2024; use the index entry or section for "Plumbing fixture layout clearances" to confirm that A water closet is commonly laid out with at least 15 in.
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