How to Install a Bathroom Vanity: From Removal to Final Caulk

Selecting the Right Vanity

Measure your space before buying anything. Record three dimensions: the width between the side walls (or between the wall and the toilet if the vanity is on one end), the depth from the wall to the front clearance zone (leave at least 21 inches of walkway in front of the vanity per IRC code), and the height from the floor to your preferred counter surface. Standard vanity heights range from 30 to 36 inches. The 36-inch comfort height has become the default in new construction because it reduces bending at the sink, but shorter users or families with small children may prefer 32-34 inches.

Stock Vanities: $150-$400

Home Depot, Lowe's, and IKEA stock vanities in standard widths of 24, 30, 36, 48, and 60 inches. The Hampton Bay Ascher 36-inch vanity ($220 at Home Depot) includes a white engineered stone countertop, an undermount porcelain sink, and a matching framed mirror. The IKEA GODMORGON 32-inch vanity ($200) uses a particleboard frame with a veneer finish and pairs with IKEA's modular drawer inserts. Stock vanities ship or are available for pickup within 1-3 days. The limitation is color and style selection: you get what is on the shelf.

Custom and Semi-Custom Vanities: $500-$2,000

Semi-custom vanities from brands like KraftMaid (available through Home Depot) or Wellborn Cabinet (available through kitchen and bath dealers) let you choose the door style, finish, countertop material, and hardware. Lead time runs 4-8 weeks. A 36-inch KraftMaid vanity in a shaker-style painted finish with a quartz countertop costs $700-$1,100. Fully custom vanities built by a local cabinetmaker start at $1,500 and go up based on wood species, finish complexity, and countertop selection. Custom work makes sense when your bathroom has an unusual layout, angled walls, or specific storage requirements that stock sizes cannot accommodate.

Wall-Mounted (Floating) Vanities

Wall-mounted vanities mount to the wall studs and leave the floor visible underneath, which makes the bathroom feel larger and simplifies floor cleaning. The Kohler Veil 30-inch wall-mounted vanity ($900) is a popular option with a solid wood frame and integrated porcelain top. Wall-mounted installation requires that the wall framing can support the vanity weight (a loaded 36-inch vanity weighs 150-200 pounds). You must open the wall and install a 2x6 or 2x8 blocking between the studs behind the vanity location. If your bathroom has a concrete slab floor, a wall-mounted vanity eliminates the need to scribe the vanity base to an uneven floor—a common frustration with floor-mounted units.

Tools and Materials Needed

• Adjustable wrench (10-inch, Crescent C10, $18)
• Basin wrench ($15, Ridgid 27017)
• Putty knife (1-1/2 inch, Hyde 06150, $8)
• Utility knife (Milwaukee Fastback, $12)
• Caulk gun ($5)
• Level (24-inch, Empire True Blue, $18)
• Drill/driver (DeWalt DCD771C2, $99)
• Stud finder (Zircon Metalert 40, $25)
• Silicone caulk: GE Silicone II Kitchen and Bath ($7 per tube)
• Plumber's putty ($3)
• Teflon pipe thread tape ($2)
• Shims ($4 per bundle)
• Supply lines: Fluidmaster 3/8-inch compression x 1/2-inch FIP ($8 per pair)
• P-trap assembly: Oatey 1-1/4-inch PVC P-trap kit ($6)
• Safety glasses and work gloves

Step 1: Remove the Old Vanity

Turn off the hot and cold water supply valves under the sink. Open the faucet to drain residual water pressure from the lines. Place a bucket and towels under the P-trap to catch standing water. Unscrew the nuts connecting the P-trap to the sink drain tailpiece and the wall drain fitting using your adjustable wrench or by hand if the nuts are plastic. Remove the P-trap and set it aside.

Disconnect the supply lines from the shut-off valves. Use the adjustable wrench on the valve side, not the supply line side, to avoid crushing the line nut. If the supply lines are corroded or the nuts are frozen, cut the lines with a tubing cutter ($12, RIDGID 32985) and replace them with new flexible supply lines. Remove the drain tailpiece from the sink basin by unscrewing the lock nut from underneath. If the vanity has a backsplash, pry it off the wall with a putty knife and a flat bar.

Unscrew the vanity from the wall. Most vanities attach to the wall with 2-1/2 or 3-inch screws driven through the back panel into wall studs. Remove these screws. If the vanity is caulked to the wall, cut the caulk line with a utility knife before pulling the vanity away from the wall. Lift the vanity straight out. If the vanity is built in place (glued and screwed to the floor), use a reciprocating saw to cut the fasteners and pry the unit free. Expect floor damage under the old vanity—water leaks over the years rot the subfloor in this area. Assess the damage and patch with 3/4-inch plywood if necessary before installing the new vanity.

Step 2: Prepare the Wall and Floor

With the old vanity removed, inspect the wall behind it. The wall may have water stains, old caulk residue, or paint damage. Scrape away loose paint and caulk with a putty knife. Patch any drywall damage with joint compound and sand smooth. If the wall behind the vanity is unfinished (exposed studs or bare drywall), tape and mud the area, then prime and paint before the new vanity goes in. Painting behind the vanity after installation is nearly impossible because the vanity back panel blocks access.

Check the floor for level. Place your 24-inch level across the floor where the vanity will sit. If the floor is out of level by more than 1/8 inch across the vanity width, you will need to shim the vanity during installation. Bathrooms with tile floors are frequently uneven due to the thickness variation between the tile and the grout lines. Note the high and low spots so you know where to place shims.

Locate the wall studs behind the vanity location using a stud finder. Mark stud centers with a pencil at the height where the vanity back rail will sit (typically 30-34 inches from the floor). The vanity must be screwed into studs, not just into drywall. Drywall alone cannot support the weight of a loaded vanity, which ranges from 100 to 250 pounds depending on size and material.

Step 3: Pre-Install the Faucet and Drain on the New Sink

Installing the faucet and drain on the sink before the sink goes into the vanity saves your knuckles and your patience. Working inside the vanity cabinet to tighten faucet nuts is awkward; working with the sink upside down on a workbench or the floor is straightforward.

Roll a rope of plumber's putty (1/4-inch diameter) around the base of the faucet. Press the faucet into the mounting holes on the sink deck. From underneath, thread the mounting nuts onto the faucet shanks and tighten by hand, then a quarter turn with a wrench. Do not overtighten; the rubber gasket and putty seal the connection, and excessive force cracks the sink basin. Wipe away excess putty that squeezes out around the faucet base.

For the drain assembly, roll plumber's putty around the drain flange (the visible part that sits in the sink basin). Insert the flange into the drain hole from above. Thread the rubber gasket, friction ring, and lock nut onto the tailpiece from below. Tighten the lock nut while pressing down on the flange to keep it seated. Connect the pop-up lift rod to the drain linkage according to the faucet manufacturer's instructions. The Delta, Moen, and Kohler faucets all use slightly different pop-up mechanisms—follow the specific diagram included with your faucet.

Step 4: Position and Secure the New Vanity

Carefully slide the vanity into position against the wall. If the vanity has a countertop and sink already attached (common with stock vanities from Home Depot and Lowe's), maneuver the unit slowly to avoid chipping the countertop edge against the wall. If the countertop is a separate piece, set the vanity cabinet first, then place the countertop on top.

Check the vanity for level front-to-back and side-to-side. If the vanity rocks or sits unevenly, slide cedar shims under the base at the low spots. Place shims at the front and back edges of the vanity, near each corner. Check level again after shimming. Once the vanity is level, drive 2-1/2-inch wood screws through the back panel of the vanity into the wall studs you marked earlier. Use at least two screws per stud. Countersink the screw heads slightly so they do not interfere with the wall behind the vanity.

Score the shims flush with the vanity base using a utility knife, then snap off the excess. The vanity should sit solidly on the floor with no rocking. If there is a gap between the vanity back and the wall, that is normal—caulk will seal it. A gap of up to 1/2 inch is acceptable; gaps wider than 1/2 inch indicate a bowed wall that should be addressed with a scribe cut on the vanity back panel or a filler strip.

Step 5: Reconnect the Plumbing

Connect the new supply lines to the shut-off valves. Wrap the valve threads with three wraps of Teflon tape in a clockwise direction (when viewed from the end of the threads). Thread the supply line nut onto the valve and tighten with an adjustable wrench—hand-tight plus a quarter turn. Connect the other end of each supply line to the faucet supply stubs. Open the shut-off valves slowly and check for leaks at every connection. If a connection drips, tighten the nut slightly. If it still drips, shut off the valve, disconnect the line, reapply Teflon tape, and reconnect.

Assemble the P-trap. Connect the tailpiece (extending down from the sink drain) to the curved trap arm with a slip nut and washer. Connect the other end of the trap arm to the wall drain fitting with a slip nut and washer. The trap arm should slope slightly downward toward the wall (1/4 inch per foot of run) to ensure proper drainage. Tighten all slip nuts by hand, then a quarter turn with pliers. Run water into the sink and check every connection for leaks. Fill the sink basin and let it drain to test the full flow rate and confirm the P-trap holds water (the water remaining in the curved section of the trap prevents sewer gases from entering the bathroom).

Step 6: Apply Caulk and Final Seals

Caulk is the last line of defense against water infiltration behind and under the vanity. Apply a continuous bead of silicone caulk (not acrylic latex—silicone is waterproof and mold-resistant) along the joint where the vanity back meets the wall. Apply a second bead along the joint where the countertop meets the wall. If the vanity has a backsplash, caulk along the top and bottom edges of the backsplash where it meets the wall and the countertop.

Use GE Silicone II Kitchen and Bath caulk ($7 per tube) in white or clear. Cut the caulk tube tip at a 45-degree angle with a small opening—start smaller than you think you need; you can always cut more. Smooth the caulk bead with a wet finger or a caulk smoothing tool ($4, Hyde 09440). Work in 2-foot sections and keep a damp paper towel handy to wipe excess off your finger and the surrounding surfaces. Silicone caulk skins over in 30 minutes and cures fully in 24 hours. Do not run water on the freshly caulked surfaces for at least 2 hours.

Caulk the underside of the countertop overhang where it meets the vanity cabinet top. This joint is invisible but prevents water from seeping behind the countertop edge and into the cabinet below. If the vanity sits on a tile floor, caulk the base where the vanity side panels meet the floor to close the gap and prevent water from wicking up into the vanity base from below.

Mistakes That Cause Leaks and Damage

Not Checking Stud Locations Before Buying

If the vanity back panel does not align with any wall studs, the screws will pull through the drywall under the weight of the vanity and its contents. Measure stud locations before purchasing and choose a vanity width that places its back rail over at least two studs. If no stock size works, add a mounting cleat (a 2x4 block screwed to the wall studs) behind the vanity for the screws to bite into.

Overtightening Drain Connections

Plastic drain nuts and porcelain sink basins crack under excessive force. Hand-tighten drain connections, then add no more than a quarter turn with pliers. If a plastic nut leaks, disassemble the connection, check that the rubber washer is seated correctly (flat side against the nut, beveled side against the surface), and reassemble. Do not fix a leak by tightening harder.

Forgetting to Remove the Sink Clip Nuts

Undermount sinks attach to the countertop with clip nuts (J-bolts) screwed into threaded inserts on the underside of the countertop. If you are replacing a vanity with an undermount sink, remove every clip nut before trying to lift the countertop off the vanity cabinet. Forgotten clips hold the countertop to the cabinet and can crack the sink or countertop when you apply upward force.

Using the Wrong Caulk

Acrylic latex caulk (such as DAP Alex Plus) is paintable and easy to work with, but it degrades in wet environments. Bathroom vanity joints are exposed to standing water, humidity, and temperature fluctuations. Use 100% silicone caulk for all bathroom vanity joints. Silicone adheres to porcelain, glass, metal, and finished wood, and it resists mold growth for 10+ years. The downside is that silicone is not paintable—if you need to paint over the caulk line, use a paintable silicone like GE Silicone II XST.

Cost Breakdown

Professional installation adds $200-$500 for a straightforward swap (same footprint, same plumbing locations). If the project requires moving plumbing, replacing subfloor, or electrical work, labor costs rise to $500-$1,200. A bathroom vanity replacement recoups 50-65% of its cost at resale according to the National Association of Realtors 2025 Remodeling Impact Report.