How to Replace Your Bathroom Vanity Cabinet

Vanity installation is the single most effective way to modernize a bathroom's aesthetic while improving storage functionality. A fresh cabinet breathes life into a tired space, but the process demands precision to ensure the new piece sits flush against the wall and level on the floor. Done well, the transition is seamless, with the cabinet secured firmly and the plumbing joints dry and leak-free. Before you begin, realize that this project is as much about plumbing as it is about cabinetry. You are working in tight, dark quarters behind the basin where mistakes are easily hidden but eventually lead to water damage. Take your time with the alignment, prioritize the seal on your waste pipe, and ensure your mounting screws bite into wall studs, not just drywall anchors.

  1. Shut Off and Drain. Shut off the water supply valves under the sink and open the faucet to relieve pressure. Place a bucket under the P-trap to catch residual water, then disconnect the supply lines and the drain pipe.
  2. Pull the Old Cabinet. Remove the vanity top first if possible to reduce weight. Unscrew the cabinet from the wall studs, then use a utility knife to score any caulk lines where the vanity meets the wall before pulling it away.
  3. Assess Floor Level. Clean the area where the old cabinet sat. Check for wall rot or moisture damage, and use a level to determine if your floor has a significant slope that will require shimming the new cabinet.
  4. Level Your Cabinet Base. Place the new vanity in position. Use cedar shims under the base to level it front-to-back and side-to-side, checking with a carpenter's level on the vanity rim.
  5. Anchor to Wall Studs. Locate the wall studs behind the cabinet back. Drill pilot holes through the cabinet's mounting strip and secure the vanity to the studs using #10 wood screws with finish washers.
  6. Reconnect All Pipes. Reattach the sink drain and P-trap, and reconnect the supply lines to the shut-off valves. Tighten all connections by hand first, then give an extra quarter-turn with a wrench to ensure a seal.
  7. Caulk the Seams. Apply a bead of silicone caulk along the seam where the vanity top meets the wall to prevent water from running behind the cabinet. Wipe away excess caulk immediately with a damp cloth.