During the rough-in phase for a two-piece water closet, a plumber measures the distance from the finished wall to the centre of the closet flange. The measurement is 280 mm (11.0 in). The client has selected a standard close-coupled water closet that requires a 305 mm (12 in) rough-in. What is the plumber's best course of action to ensure a code-compliant and functional installation?

Question: During the rough-in phase for a two-piece water closet, a plumber measures the distance from the finished wall to the centre of the closet flange. The measurement is 280 mm (11.0 in). The client has selected a standard close-coupled water closet that requires a 305 mm (12 in) rough-in. What is the plumber's best course of action to ensure a code-compliant and functional installation?

Answer options:

• Install the closer coupled water closet as planned, as a 25 mm difference is negligible.
• Use an offset closet flange to achieve the correct rough-in distance. ✅ Suggest a different water closet model designed for a 280 mm rough-in.
• Adjust the wall construction to move it back by 25 mm relative to the flange.

Correct answer: Suggest a different water closet model designed for a 280 mm rough-in.

Explanation: A 25 mm difference in rough-in for a water closet is significant and will prevent proper installation. The most practical and often cost-effective solution is to select a water closet specifically designed for a 280 mm rough-in. Using an offset flange may work but can be problematic for maintenance or subsequent replacements. Adjusting the wall is a major construction change, and ignoring the difference is not acceptable.