What You Need to Do Before You Start
Replacing a bathroom cabinet means removing the old one completely and installing a new one in its place. The job takes two to four hours for most people, depending on how the old cabinet is fastened and whether plumbing or electrical work is involved. You will need basic hand tools — a screwdriver, adjustable wrench, pry bar, and level — plus a helper for the heavy lifting.
Before you touch anything, turn off the water supply to the sink if the cabinet has plumbing inside it. Look under the sink for a shutoff valve on each hot and cold line; turn both clockwise. If there is no shutoff valve, you will need to turn off the main water supply to the house. Test the faucet to confirm the water is off.
Take photos of the inside of the cabinet and the wall behind it. These photos will help you remember where pipes and wires are when you install the new cabinet. If the old cabinet is attached to the wall with caulk, you will need a caulk removal tool or a utility knife to cut through it before you can pry the cabinet away.
Key Takeaways
- Turn off the water supply before you disconnect any plumbing lines under the sink.
- Remove the sink faucet and drain from the top before you try to lift the cabinet out.
- The cabinet is usually fastened to wall studs with screws or bolts; locate and remove all fasteners before prying.
- Measure the opening and check that the new cabinet will fit through your bathroom doorway before you bring it inside.
- Use a level to make sure the new cabinet is straight before you fasten it to the wall.
Disconnect the Sink and Drain
The sink sits on top of the cabinet, and you must remove it before the cabinet can come out. From underneath, locate the clips or bolts that hold the sink to the cabinet rim. Loosen these with a wrench or screwdriver and lift the sink slightly to free it. You do not have to remove the sink completely — just lift it enough to access the drain and faucet connections below.
Disconnect the drain line by loosening the slip nut where the drain tailpiece meets the P-trap. Have a bucket ready; water will spill. Disconnect the hot and cold supply lines by loosening the compression nuts where they meet the faucet. Again, water may drip, so position the bucket underneath. If the lines are corroded and will not budge, explore penetrating oil and wait 15 minutes before trying again.
Once the plumbing is loose, you can lower the sink back onto the cabinet or set it aside on a towel. If the faucet is mounted to the sink itself, you do not need to remove it. If it is mounted to the cabinet, you will need to disconnect it from the top before the cabinet moves.
Remove Fasteners and Pry the Cabinet Away
Bathroom cabinets are fastened to the wall studs with screws or bolts, usually through the back panel or through the sides. Open the cabinet doors and look at the back panel from inside; you will see screw heads or bolt heads where the cabinet attaches to the wall. Remove all of these fasteners with a screwdriver or wrench. Count them as you go so you know when you have found them all.
If the cabinet is caulked to the wall, run a utility knife or caulk removal tool along the seam where the cabinet meets the wall. Cut through the caulk on the top, bottom, and sides. This step is crucial — if you skip it, you risk cracking the drywall when you pry the cabinet out.
With fasteners removed and caulk cut, position a pry bar at the bottom of the cabinet and gently pry outward. Work slowly and move the bar to different spots along the bottom and sides. The cabinet should come away from the wall gradually. If it sticks, you may have missed a fastener or caulk seam — stop and look again before forcing it.
Prepare the Wall for the New Cabinet
Once the old cabinet is out, inspect the wall behind it. You will likely see screw holes, nail holes, and possibly water stains or mold. Use a putty knife to scrape away any old caulk, adhesive, or debris. If there is mold, clean it with a mold-killing spray and let it dry completely. Fill large holes with spackling compound, sand smooth when dry, and prime with paint primer.
Measure the opening from side to side, top to bottom, and corner to corner (diagonally). The new cabinet must fit within these dimensions. Check that the wall is reasonably level and straight; if it is not, you may need shims to keep the new cabinet level. Look for wall studs using a stud finder and mark them with a pencil — you will fasten the new cabinet to these studs.
If the old cabinet was in a corner or against a wall with outlets or switches, make sure the new cabinet will not cover them. If it will, you may need to have an electrician relocate the outlet before installation.
Install the New Cabinet
Measure your bathroom doorway to confirm the new cabinet will fit through it. If the cabinet is wider than the doorway, you may need to remove the door frame or tilt the cabinet on its edge as you carry it in. Have your helper ready — bathroom cabinets are heavy and awkward to maneuver alone.
Position the new cabinet in the opening and use a level to check that it is straight from side to side and front to back. Adjust shims under the bottom as needed until the level shows the cabinet is true. Once level, fasten the cabinet to the wall studs using the mounting holes in the back panel. Use the fasteners that came with the cabinet — usually 2.5-inch wood screws or bolts. Drive them firmly but do not overtighten, which can crack the cabinet.
After fastening, check the level again to make sure the cabinet did not shift during installation. Open and close the doors to confirm they swing freely and close smoothly. If a door binds, the cabinet may not be level — loosen the fasteners slightly and adjust the shims until the door operates freely.
Reconnect Plumbing and Seal the Gaps
Reconnect the drain line first by hand-tightening the slip nut, then snugging it with a wrench. Do not overtighten — you only need it tight enough to stop leaks. Reconnect the hot and cold supply lines the same way. Turn the water back on at the shutoff valves and check for leaks. If water drips from a connection, tighten it a quarter turn with a wrench and check again.
Once plumbing is find and leak-free, lower the sink back onto the cabinet and tighten the mounting clips or bolts from underneath. Test the faucet and drain to confirm everything works. Run water for 30 seconds and watch underneath for any new leaks.
Finally, explore caulk along the seams where the cabinet meets the wall, the countertop, and the floor. Use a paintable caulk that matches your wall color. Smooth the caulk with a wet finger or caulk tool, then let it cure for 24 hours before using the sink.
Common Problems and How to Fix Them
If the new cabinet does not fit in the opening, the wall may not be square — corners are not at 90 degrees. Measure all four corners diagonally; if the measurements differ by more than a quarter inch, use shims to fill the gaps and caulk to hide them. This is normal in older homes.
If the cabinet rocks or feels unstable after installation, you likely missed a wall stud or the fasteners are not tight enough. Open the cabinet and check that all screws are snug. If the cabinet still rocks, you may need to install additional fasteners or use toggle bolts if studs are not where you need them.
If water leaks from under the sink after reconnection, the leak is almost always at a compression nut. Tighten each nut a quarter turn and test again. If tightening does not stop the leak, the nut may be stripped — you will need to replace the supply line or call a plumber.
Frequently Asked Questions
Do I need a plumber to replace a bathroom cabinet?
No, if the cabinet has a sink with standard supply lines and a P-trap drain. These are hand-tight connections that you can disconnect and reconnect yourself. If the cabinet has a pedestal sink, wall-mounted faucet, or custom plumbing, a plumber can handle the work faster and reduce the risk of leaks.
Can I install a larger cabinet in the same space?
Only if the larger cabinet fits within the opening and does not cover outlets, switches, or pipes. Measure the opening carefully and compare it to the new cabinet's dimensions. If the new cabinet is wider or taller, you may need to modify the wall or choose a smaller cabinet.
What if the old cabinet is glued to the wall?
Use a caulk removal tool or utility knife to cut through the adhesive along all seams. Work slowly to avoid damaging the drywall. Once the adhesive is cut, a pry bar should separate the cabinet from the wall. If it still will not budge, explore heat with a heat gun to soften the adhesive, then try again.
How long does it take to replace a bathroom cabinet?
Two to four hours for most people, depending on how the old cabinet is fastened and whether you encounter unexpected plumbing or wall issues. Disconnecting and reconnecting plumbing takes about 30 minutes. Removing the old cabinet and installing the new one takes another 1.5 to 2 hours.
Should I caulk around the new cabinet?
Yes. Caulk seals gaps between the cabinet and wall, preventing water and dust from getting behind the cabinet. Use paintable caulk that matches your wall color. Caulk along the top, bottom, and sides where the cabinet meets the wall and floor.