How to Install a Double Sink Vanity | Step-By-Step Swap

Installing a double sink vanity takes a weekend, basic plumbing skills, and careful measuring before you start.

Most double-sink vanities run about 60 inches wide, so the first question isn’t “how” — it’s “will it fit?” Before you buy anything, measure the opening, check the plumbing rough-in positions, and confirm the supply lines and drain outlets line up with the new cabinet’s holes. Skip that step and you’re making return trips to the store mid-project.

This walkthrough covers the full swap: removing the old vanity, setting and leveling the new cabinet, mounting the sinks and faucets, connecting the plumbing, and leak-testing everything. If you’re still shopping, a tested roundup of 60-inch double sink vanity cabinets can narrow the field before you commit.

What You Need Before Starting

Gather the basics first. Shutoff valves on the hot and cold supply lines, a bucket for residual water, an adjustable wrench, a stud finder, a level, shims, a drill with a pilot bit, screws, plumber’s putty, and silicone caulk cover nearly every step.

Turn off the water at the shutoff valves under the sink, then open the faucet to relieve pressure. Disconnect the supply lines and the P-trap, keeping the bucket underneath to catch what drains out. If there are no local shutoffs, close the main water valve instead.

Removing the Old Vanity

Clear the cabinet: remove doors and drawers so the unit is lighter and easier to maneuver, and so you can see how it’s fastened. Check for screws driven through the back panel into wall studs, plus any caulk bead sealing the top edge to the wall or countertop.

Cut through the caulk with a utility knife, pull the fasteners, and slide the old cabinet out. If the vanity top is a separate piece from the cabinet, detach it first — many are just sitting on the cabinet frame and held by a few clips.

You can skip the gut renovation if the existing plumbing lines up with the new cabinet’s cutouts. But if you’re converting a single-sink setup to two sinks, the supply lines and drains likely need re-routing before anything else happens. That’s a bigger job than a cabinet swap and may need a plumber.

Setting, Leveling, and Securing the Cabinet

Position the new vanity against the wall and check the fit.

Run a level across the top of the cabinet front to back and side to side, using shims under the base to close any gaps. Once it’s level, find the studs with a stud finder and mark them. If a pilot hole doesn’t line up with a stud, use a wall anchor rated for the cabinet’s weight instead.

Installing the Sinks, Faucets, and Drain Plumbing

The sequence matters here. Most guides — including Home Depot’s — recommend assembling the faucet and drain on the sink before the top goes into its final position, because reaching them afterward is miserable.

For an undermount sink vanity, the sink-to-top bond has to happen first. Then the assembled vanity sits for a full 24 hours so the silicone fully cures before the faucet and drain go in.

For a drop-in top, the order shifts. On the faucet and spout openings, This Old House uses plumber’s putty; at the sink flange, use silicone caulk instead, because putty can stain some sink materials.

Position matters on a double vanity. That spacing keeps the sinks balanced and leaves room for the faucets.

Once the top is set and cured, connect the hot and cold supply lines with an adjustable wrench, attach the drain assemblies and P-traps, and hand-tighten everything before you snug it down.

Leak Testing and Finish

Turn the supply valves back on and run both faucets, hot and cold. Check every joint — supply lines, shutoff valves, drain connections, and the P-trap — for drips. Tighten anything that weeps, then check again. This is the step every source agrees you can’t skip; a leak behind a closed cabinet door can go unnoticed for weeks.

Seal the gap between the vanity top and the wall with silicone caulk and let it cure overnight before using the sink normally. The full cure time protects the seal from water exposure.

If the project is for a remodel and you’re planning around the 60-inch standard, most double vanities at that width fit a standard 60-inch alcove with minimal adjustment. Just verify your rough-in plumbing matches before you commit to the layout.