Step 6 · Mount the Outlet Box
Prepare the washing machine outlet box by removing the knockouts for the hot, cold, and drain connections. Feed the PEX pipes and the PVC drain pipe through the corresponding holes in the back of the box. Insert the box into the opening in the wall, pressing it firmly against the 2x4 blocking you installed. The front flange of the box should be flush with the face of the drywall. Secure the box to the blocking using the mounting clips or screws provided with the unit.