How to Install a New Bathroom Vanity:
Pro Tip: Tom Silva, This Old House general contractor, advises letting a helper handle much of the disconnection work: turn the shut-off valves clockwise to stop the water, then use a razor knife to relieve the caulking on a self-rimming sink so you can pop it out cleanly. As Tom notes, the only thing holding a self-rimming sink to the countertop is caulking, so cutting that seal carefully makes removal much easier.
- Shut the hot and cold water lines off.
- Disconnect the sink from the P-trap and break the hose connections to the faucet.
- Use the utility knife to break the seal between the sink and the countertop. Then, carefully pry the sink away from the countertop with a hammer and a pry bar.
- Remove the screws holding the vanity to the wall and remove the vanity.
- Shut the water off to the house and cut the hot and cold water lines. Cut the P-trap as well. This will make it so only small holes need to be cut in the back of the new vanity.
- Measure the distance from the wall to the hot line and cold line. Next, measure the distance from the floor to the hot and cold lines. Transfer these measurements to the back of the vanity and cut out holes with the hole saw.
- Move the new vanity into place. Check it for level and screw it into the wall.
- Connect new shutoff valves to the hot and cold lines.
- Flip the countertop upside down and mount the sink to the countertop with silicone caulking and sink clips.
- Connect the faucet to the countertop using the plumber’s putty and the mounting brackets.
- Connect the hot and cold water lines to the faucet, then connect the drain pipe and the pop-up drain.
- Once all the connections are made, flip the counter right side up and place it on the cabinet.
- Make a new P-trap connection with the drain and connect the hot and cold water lines to the shutoff valves.
- Turn the water back on.
Technique Detail: When cutting plumbing holes in the back of the new vanity, 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, pushing the pilot bit through the vanity’s plywood back, then finish the cut from the inside to avoid tear-out.
Technique Detail: According to This Old House Magazine, when prepping the rough plumbing, place a bucket under the copper supply lines and use a compact tubing cutter to shear them both off about 2 inches from the wall. Tighten the cutter slightly after each turn around the tube to avoid distorting the soft copper.
Resources:
Plumbing Prep: Before disconnecting any supply lines, make sure you have the right wrenches on hand — typically a basin wrench for hard-to-reach faucet nuts and an adjustable wrench for supply connections. Richard also relies on plumber’s putty to seal the drain flange and PVC glue to secure new drain fittings, so have both ready before you begin the swap.
All the tools Richard used for the project, including wrenches, plumber’s putty, and PVC glue, can be found at home centers and plumbing supply stores.
The vanity and countertop were custom-ordered by the homeowner.
Vanity Selection Note: When choosing a bathroom vanity, consider whether a stock, semi-custom, or fully custom-ordered unit best suits your space. Custom vanities, like the one in this project, allow homeowners to specify exact dimensions and finishes, but stock vanities from home centers can be a practical alternative for standard-sized bathrooms. Either way, confirm that your plumbing supply lines and drain align with the vanity’s cabinet openings before installation day.
