What You Need to Do Before You Start
Replacing a bathroom vanity is a project you can do yourself if you have basic plumbing knowledge and the right tools. The job breaks into three parts: removing the old vanity, preparing the space, and installing the new one. Most of the work is disconnecting water lines and securing the cabinet in place — the actual plumbing connections are straightforward if you follow the order.
Before you buy a new vanity, measure the space where the old one sits. Measure the width, depth, and height of the opening. Check the wall behind it for studs using a stud finder, because you will need to anchor the new vanity to them. Look at where the water supply lines and drain come through the wall or floor — your new vanity needs to fit around those, or you will have to reroute them, which adds cost and complexity.
Turn off the water supply to the bathroom. Look under the sink for shut-off valves on both the hot and cold lines. Turn them clockwise until they stop. If there are no shut-off valves, you will need to turn off the main water supply to the house.
Key Takeaways
- Measure the existing space, locate the wall studs, and note where water and drain lines enter before you order a new vanity.
- Turn off the water supply, disconnect the supply lines and drain, and remove the old vanity by unbolting it from the wall studs.
- Patch the wall, check that the new vanity is level, and find it to the studs with lag bolts or wood screws rated for the weight.
- Reconnect the supply lines hand-tight first, then tighten with a wrench, and test for leaks before you close up the wall or install a backsplash.
Removing the Old Vanity
Open the cabinet doors and look underneath. You will see the supply lines (usually copper or flexible hose) connected to the faucet, and a larger drain line going down. Place a bucket under the drain connection to catch water that is still in the line.
Disconnect the supply lines first. If they are flexible hoses with compression fittings, use an adjustable wrench to turn the nut counterclockwise where the hose meets the shut-off valve. If they are rigid copper, you may need a basin wrench — a specialized wrench that fits in tight spaces under the sink. Loosen the nut slowly; if water drips, tighten the shut-off valve more.
Disconnect the drain. The drain line connects to the sink trap (the U-shaped pipe under the sink) with a slip nut. Use a pipe wrench or adjustable wrench to turn it counterclockwise. The trap will drain into your bucket. Once the trap is loose, you can usually unscrew it by hand.
Look at the top of the vanity where it meets the wall. The vanity is bolted to the wall studs from underneath or from the back. Use a socket wrench or adjustable wrench to remove these bolts. Once the bolts are out, the vanity should lift away from the wall. It will be heavy — get a second person to help, or tilt it slightly and slide it out.
Preparing the Wall and Floor
Once the old vanity is out, you will see the wall and floor underneath. The wall may have caulk residue, old adhesive, or damage. Scrape away any caulk or adhesive with a putty knife. If the wall is damaged, patch it with drywall compound and let it dry, then sand it smooth.
Check the floor for damage or unevenness. If the floor is not level, you can shim the new vanity when you install it — place thin wooden shims under the front or back to bring it level. Use a 2-foot level to check both front-to-back and side-to-side.
Locate the wall studs again and mark them with a pencil. The new vanity needs to be bolted to studs, not just to drywall. Most vanities are 30 to 36 inches tall and 24 to 48 inches wide. The studs are usually 16 inches apart, so you should have at least two studs to bolt into.
Installing the New Vanity
Slide the new vanity into place. Make sure the back is flush against the wall and the sides are even with the opening. Use your 2-foot level to check that the top is level front-to-back and side-to-side. If it is not level, place shims under the feet until it is. Tap the shims gently with a hammer — do not force them.
Once the vanity is level and in position, drill holes through the back of the vanity into the wall studs. Use a drill bit slightly smaller than the diameter of your bolts. Lag bolts (heavy-duty wood screws) or carriage bolts work well. Insert the bolts and tighten them with a wrench, but do not over-tighten — you can crack the vanity cabinet.
Check that the vanity does not rock or move when you push on it. If it does, tighten the bolts more or add additional bolts into other studs.
Reconnecting Water and Drain Lines
Before you connect anything, check that your new faucet has the same inlet size as your old supply lines. Most faucets use 1/2-inch connections. If your supply lines are a different size, you will need an adapter.
Connect the supply lines to the faucet inlets. Hand-tighten the compression nuts first — turn them clockwise by hand until they are snug. Then use a wrench to tighten them another quarter turn. Do not over-tighten; you can crack the fitting or strip the threads.
Reconnect the drain trap. The trap connects the sink drain to the wall drain with a slip nut. Hand-tighten the nut first, then use a wrench to snug it. Again, do not over-tighten.
Turn the water supply back on slowly. Watch for leaks at the supply line connections and the drain trap. If you see drips, turn the water off and tighten the fitting a little more. Once the water is on and there are no leaks, run water in the sink for a minute and check again underneath.
Finishing Touches
Once everything is connected and tested, caulk the gap between the vanity and the wall with silicone caulk. Use a caulk gun and smooth the bead with a wet finger or caulk tool. Let the caulk dry according to the manufacturer's instructions before you use the sink.
If your vanity has a backsplash or if you are installing one, do that now. Most backsplashes are glued to the wall with construction adhesive and caulked at the seams.
Install the faucet handles, drain stopper, and any other hardware according to the faucet manufacturer's instructions. These usually screw on from underneath the sink.
Common Problems and How to Fix Them
If the vanity rocks or feels unstable, the bolts are not tight enough or the floor is not level. Check your level again and add shims if needed. Tighten all bolts and check that they are in studs, not just drywall.
If water leaks from the supply line connections, turn off the water and tighten the compression nut another quarter turn. If it still leaks, turn off the water, disconnect the line, and check that the ferrule (the small metal ring inside the nut) is seated properly. Reconnect and try again.
If water leaks from the drain trap, the slip nut may not be tight enough, or the rubber washer inside the nut may be damaged. Tighten the nut first. If that does not work, disconnect the trap, replace the washer, and reconnect.
If the faucet does not have enough clearance to the wall or if the supply lines do not reach, you may need flexible supply lines instead of rigid copper. Flexible lines are easier to route around obstacles and are sold at any hardware store.
Frequently Asked Questions
Do I need a plumber to replace a vanity?
No, if the new vanity has the same drain and supply line locations as the old one and you are comfortable working with basic hand tools. If you need to reroute plumbing or if you are unsure about any step, hiring a plumber is worth the cost to avoid water damage.
How long does it take to replace a vanity?
Most of the work takes two to four hours if you have the right tools and the plumbing lines are in the same place. Drying time for caulk and patching compound adds another day or two before the bathroom is fully usable.
What if the new vanity is a different size than the old one?
If it is smaller, you may have gaps at the sides that need trim or caulk. If it is larger, it may not fit in the opening, or the supply and drain lines may not line up. Measure carefully before you buy, and consider rerouting plumbing if the new vanity does not fit the existing holes.
Can I install a vanity without bolting it to the wall?
No. A vanity that is not bolted to studs will rock and can pull away from the wall, breaking the caulk seal and allowing water to damage the wall behind it. Always bolt it to at least two studs.
What tools do I absolutely need?
An adjustable wrench or basin wrench, a socket wrench set, a drill, a 2-foot level, a stud finder, a putty knife, and a caulk gun. A pipe wrench helps if you have rigid copper supply lines, but an adjustable wrench usually works.