How To Replace a Bathroom Vanity

Replacing an old, worn-out bathroom vanity can dramatically improve the way your bathroom looks and boost your bathroom’s storage and function. This project requires mid-level carpentry and plumbing skills, but it’s a task many homeowners can tackle with the right tools and guidance. In the video above, This Old House plumbing and heating contractor Richard Trethewey demonstrates the process of installing a new bathroom vanity.

Preparing for the Project

To successfully replace your bathroom vanity, you’ll need the following tools and materials:

• Adjustable wrench
• Caulk gun
• Compass saw
• Drill/driver
• Flat pry bar
• Jigsaw
• New vanity cabinet and top
• Plumber’s putty
• Propane torch
• PVC primer and cement
• Reciprocating saw
• Shut-off valves
• Silicone adhesive
• Tubing cutter
• Utility knife
• Water supply lines

Pro Tip: Richard Trethewey advises: Never use a hacksaw to cut tubing — it may leave the tube’s end rough or crooked and unsuitable for soldering. Use a tubing cutter instead, and take it slow on the first revolution to make sure the cutting wheel stays in its groove. He also warns that when soldering an angle stop, make sure it’s open: “If it’s not, the torch will heat up the air in the tube and cause it to pop right off.”

A few often-overlooked tools belong on your list as well: a basin wrench, essential for tightening the nuts on faucet valves and spouts in the virtually inaccessible regions under the sink’s basin; a wire brush for cleaning inside copper tubing before soldering; fine-grit sandpaper for polishing the outside of copper tubing; and flux, the acidic paste applied to copper before soldering. Also keep a spray bottle filled with water and a damp cloth nearby when soldering to prevent fires and to wipe freshly soldered joints clean.

Removing the Old Vanity

The first step in replacing your bathroom vanity is removing the old one:

1. Shut off the hot and cold water supply valves under the sink.
2. Disconnect the sink trap from the tailpiece (vertical drainpipe) by hand.
3. Use an adjustable wrench to disconnect the hot and cold water supply lines from the shut-off valves.
4. Cut through the old caulk around the sink bowl using a utility knife.
5. Pry the old sink bowl from the vanity top using a flat pry bar.
6. Unscrew the vanity top from the cabinet using a drill/driver and remove it.
7. Cut out the floor of the vanity using a reciprocating saw to make removal easier.

Installing the New Vanity

With the old vanity removed, it’s time to install the new one. You can watch Trethewey walk through the installation steps, from positioning the cabinet to making necessary modifications.

Start by placing the new vanity cabinet in its intended location. You may need to make some adjustments to accommodate existing plumbing and electrical fixtures. Ensuring the right positioning will simplify the subsequent steps and modifications.

Next, modify the new vanity to fit around existing plumbing and electrical components. Here are some key steps:

• Reposition water supply pipes: If the existing water supply pipes don’t align with the new vanity, you may need to cut and solder new copper pipes. This might involve turning off the main water supply, draining the pipes, and using a propane torch for soldering.
• Notch the cabinet back: To accommodate the existing drainpipe, use a handsaw to notch the cabinet back. This will ensure a snug fit and help maintain the cabinet’s structural integrity.
• Cut an opening for an electrical outlet: If an electrical outlet is present, you may need to cut an opening in the vanity’s side. Using a jigsaw, carefully cut the required size for the outlet box and secure it with Madison bars.

Pro Tip: Richard Trethewey, This Old House plumbing and heating expert, secures the vanity cabinet to the wall by drilling through the cabinet in two places with a high-speed drill bit, then using a masonry bit to go through ceramic tile before installing anchors. To hold the countertop down to the vanity, he recommends applying a silicone bead right along the top of the cabinet before setting the countertop in place.

Technique Detail: When cutting plumbing holes in the vanity back, use a ¾-inch-diameter hole saw for the supply lines and a 1½-inch-diameter saw for the drainpipe. Start the hole from the outside of the cabinet, pushing the pilot bit through the vanity’s plywood back, then finish the cut from the inside to avoid tear-out.

Vanity Plumbing Connections

Here’s how to handle the new plumbing connections so your new sink works as well or better than the old one.

Installing New Shut-off Valves

Replace the old shut-off valves with new ones to prevent leaks. Tighten the connections securely using an adjustable wrench. New shut-off valves can enhance the reliability and longevity of your bathroom plumbing system.

Connecting Water Supply Lines

Connect the new water supply lines to the shut-off valves and the sink faucet. Use stainless steel braided connections for durability and ease of installation. These connections are designed to be flexible and are less likely to leak over time.

Setting Up the Drain

To set up the drain, apply plumber’s putty around the sink drain. Set the drain in the sink’s hole and tighten the nut from below. Remove any excess putty that squeezes out from under the drain flange. Use PVC primer and cement to connect the plastic drainpipe.

Making Additional Plumbing Connections

Beyond the basic setup, make sure all connections are tightened securely. Use thread seal tape on threaded connections to prevent leaks. Double-check the alignment of pipes to ensure there are no kinks or bends that could impede water flow.

Securing the Vanity and Countertop

For safety and strength, secure your vanity and countertop to the wall. Securing the vanity will prevent it from shifting over time, ensuring it remains stable and aligned.

Use a high-speed drill bit to create holes through the cabinet back. Drill into the wall with a masonry bit if you’re going through ceramic tile. Install anchors in the wall if necessary. Then, screw the vanity cabinet securely to the wall.

To attach the countertop to the vanity, apply a continuous bead of silicone adhesive around the top edge of the vanity. Carefully set the vanity top into place, ensuring it’s level and properly aligned. Allow the adhesive to dry according to the manufacturer’s instructions.

Before moving on to the finishing touches, check the alignment and level of the vanity and countertop. Make any necessary adjustments to ensure everything is in place and properly aligned.

Vanity Finishing Touches

The final steps in your vanity replacement project involve ensuring everything is connected and functioning.

Testing the Plumbing

Testing the plumbing ensures that there are no leaks and that everything is functioning as expected. Take your time to inspect each connection carefully. Turn on the water supply at the main shut-off valve. Check all connections for leaks, tightening as necessary. Run water through the faucet and check the drain for proper function.

Caulking and Cleanup

Caulking creates a seal that prevents water from seeping behind the vanity, protecting your walls and floor from moisture damage. Apply a bead of caulk around the edges of the vanity where it meets the wall and floor.

Clean up any debris or dust from the installation process, and wipe down the new vanity and countertop to remove any fingerprints or smudges.

Inspecting Your Work

After completing the installation, inspect your work carefully. Ensure that all plumbing connections are tight and that there’s no movement in the vanity or countertop. Also, check for any gaps in caulking that need to be addressed.

Setting Up for Use

Once everything is confirmed to be in working order, you can set up the vanity for regular use. Organize your bathroom items, place decorative accessories on the countertop, and enjoy your revitalized bathroom.