Prior to drywall, the rough-in phase requires testing of which systems?

• A. Water distribution and sanitary drainage
• B. Gas piping and electrical wiring
• C. Insulation and vapor barrier
• D. Pipes in the walls

Answer: (A)

In rough-in, catching leaks before walls go up is essential. The main idea is to verify plumbing lines—both the water supply and the sanitary drainage—work properly and won’t leak once the walls are closed in. These systems are pressure-tested: water supply lines are pressurized to a specified level, and the drainage system is tested (often with a hydrostatic or air test) to ensure joints and connections hold without leaks. If a leak shows up, you can fix it now rather than after drywall is installed, which prevents water damage, mold, and costly rework.

Gas piping and electrical wiring are important and inspected, but their testing isn't focused on the same pressure-leak checks used for water and drainage in rough-in. Insulation and vapor barrier aren’t tested for leaks, and simply identifying pipes in the walls isn’t a testing step.