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CT Plumber: Fixtures, faucets, and fixture fittings

CT Plumber · Work through your exam, one topic at a time.

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Fixtures, faucets, and fixture fittings

Domain 3 - Fixtures, faucets, and fixture fittings

This domain tests fixture selection, spacing, water conservation, materials, and accessibility. Expect clearance dimensions, flow and flush rates, and the fittings that protect the potable supply.

Space and clearance

  • Water closets: 15 in. from the centerline to any side wall or partition, a clear width of 30 in., and 21 in. of clear space from the front of the bowl to any obstruction.
  • Lavatories: 15 in. from centerline to a side wall. Urinals: minimum 15 in. center to center in most layouts; confirm any local amendment.
  • Accessible fixtures follow ICC A117.1 and ADA: water closet seat 17–19 in. above the floor, lavatory rim 34 in. maximum with 29 in. knee clearance, grab bars 33–36 in. above the floor, controls operable without tight grasping.

Water use and materials

  • Federal standards set the numbers: 1.28 gal per flush water closets, 1.0 gal per flush urinals, 2.2 gpm kitchen and residential lavatory faucets at 60 psi, 0.5 gpm for public lavatory faucets, 2.5 gpm showerheads at 80 psi.
  • "Lead-free" for wetted surfaces means a weighted average of not more than 0.25 percent lead.
  • Fixture drain outlets: 1¼ in. lavatory, 1½ in. kitchen sink and tub, 2 in. urinal and floor drain, 3 in. and larger water closet and service sink.
  • Every fixture must be listed and installed per its instructions. A flushometer valve needs adequate flowing pressure, typically 15–25 psi at the valve.

Worked example

A commercial restroom remodel replaces a 1.6 gal-per-flush tank water closet with a sensor flushometer model. Reasoning: the flush volume is compliant (1.28 gpf), but a flushometer needs minimum flowing pressure at the valve, so static pressure at the furthest fixture must be measured, not inferred from street pressure, and the branch sizing rechecked. The fixture must still hold 15 in. side clearance, 30 in. width, and 21 in. front clearance, and it needs a 3 in. drain. The answer is to verify pressure and drain size, not merely the gpf rating.

Where marks are lost

  • Measuring water closet clearance from the tank instead of the bowl front.
  • Applying residential faucet flow rates to a public lavatory, where 0.5 gpm applies.
  • Setting a tank-type water closet on a flange that does not match its rough-in dimension.