Step 2 · Open the Wall
First, use a stud finder to locate the studs that frame the bay where your plumbing will be installed. Mark the stud locations. To create the access opening, use a sharp utility knife to score the perimeter of the area you intend to remove. Then, using a drywall saw or a reciprocating saw with a suitable blade, carefully cut along your scored lines. The opening should be large enough to provide ample room to work with pipes, typically from the floor to about 48 inches high and spanning the full width between two studs. Remove the cut piece of drywall and set it aside if you plan to reuse it.