Behind-the-wall shower repairs require precision and the right parts. This College Park residence needed attention to a leaking shower valve that was causing water intrusion into the adjacent room. We accessed the valve through an existing panel, replaced the cartridge and trim components, and upgraded the shutoff valves to quarter-turn ball valves for easier maintenance. After reassembly, we ran hot and cold water through multiple cycles to confirm proper mixing and zero leaks. The shower now operates smoothly with perfect temperature control.