For a lavatory installation, the center line measurement is 19 inches.

For a lavatory installation, the center line measurement is 19 inches.

• A. 18 Inches
• B. 19 Inches
• C. 20 Inches
• D. 21 Inches

Answer: (B)

Centerline height is the vertical distance from the finished floor up to the centerline of the sink drain. This measurement sets where the tailpiece and trap will connect and keeps the lavatory, vanity, and plumbing aligned for proper drainage and cabinet clearance. For a typical lavatory installation, about 19 inches from the floor to the drain centerline is standard. This height accommodates the vanity’s countertop and basin while allowing the P-trap to fit under the sink without interference. If the centerline were lower (around 18 inches) the trap could sit too high in relation to the vanity, and if it were higher (20–21 inches) it could reduce knee clearance or require a different cabinet setup. Therefore, 19 inches is the best choice for this scenario.

Centerline height is the vertical distance from the finished floor up to the centerline of the sink drain. This measurement sets where the tailpiece and trap will connect and keeps the lavatory, vanity, and plumbing aligned for proper drainage and cabinet clearance. For a typical lavatory installation, about 19 inches from the floor to the drain centerline is standard. This height accommodates the vanity’s countertop and basin while allowing the P-trap to fit under the sink without interference. If the centerline were lower (around 18 inches) the trap could sit too high in relation to the vanity, and if it were higher (20–21 inches) it could reduce knee clearance or require a different cabinet setup. Therefore, 19 inches is the best choice for this scenario.