Residential Building Inspector B1Building Planning and Life SafetyHard

A residential building inspector is performing a rough-in inspection for a new dwelling. The plans show a shower compartment. What is the minimum required finished interior dimension from the shower control wall to the opposing wall?

  1. A24 inches
  2. B36 inches
  3. C32 inches
  4. D30 inches
Show answer & explanation

Correct answer: D. 30 inches

IRC R307.1 states that shower compartments shall have a minimum of 900 square inches (0.58 m2) of interior cross-sectional area and shall be capable of encompassing a 30-inch (762 mm) diameter circle. The minimum dimension for the 30-inch diameter circle is 30 inches. Therefore, the minimum finished interior dimension from the control wall to the opposing wall must be 30 inches.

Why the other options are wrong

  • A. This dimension is insufficient to encompass a 30-inch diameter circle.
  • B. This dimension exceeds the minimum requirement but is not the minimum.
  • C. While 32 inches is a common shower pan size, the code minimum is capable of encompassing a 30-inch diameter circle, which means a 30-inch minimum dimension in all directions.

Shower Compartment Minimum Size

Minimum interior dimensions and area required for a shower compartment to ensure usability and safety.

  • Minimum area of 900 sq inches.
  • Must accommodate a 30-inch diameter circle.
  • Critical for user comfort and safety.

Memory trick: For a shower to feel just right, 30 inches wide, a comforting sight.

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