Step 3 · Access the Valve Body
Since we've assumed there is no pre-existing access panel, one must be created. Locate the wall directly behind the shower faucet. Use a stud finder to locate the studs on either side of the plumbing. Plan to cut an opening large enough to comfortably work in, typically about 12x12 inches. Mark your cut lines on the drywall using a pencil and a level. Use a drywall saw to carefully cut along the lines. Be cautious not to cut too deep and damage any pipes or wires that may be inside the wall. Once the square is cut, remove the piece of drywall to expose the faucet valve and plumbing.