Replacing a Double Vanity

Replacing a double vanity that's already in place is a fundamentally different — and easier — project than converting a single sink to two. The hard, expensive part of a two-sink setup is the plumbing inside the wall: two drains, two vents, two supply pairs. When you're replacing an existing double vanity, all of that is already roughed in to code. You're not opening the wall or running new pipe; you're matching a new cabinet and top to plumbing that already exists. That's why a like-for-like double swap often takes a day or two instead of a week.

This guide covers what actually matters when you replace a double vanity: measuring the wall and matching the two drain and supply locations to your new cabinet, choosing between standard 60 and 72-inch widths, deciding on one continuous slab versus two prefab tops, handling two faucets, and the leveling that a long cabinet demands on a Sacramento slab-on-grade floor. It's written from the perspective of a master bathroom remodel in a Northern California home, where hard water, 1960s–80s ranch layouts, and flat-poured slabs all shape the install.

Why homeowners replace a double vanity

A double vanity is usually the visual anchor of a master bath, so when it dates the room, the whole bathroom feels old. The most common reasons people swap one out:

• Worn or damaged cabinet. Water-swollen particleboard, peeling laminate, or a cracked cultured-marble top that's past refinishing.
• Dated style. A honey-oak or builder-beige double vanity pulls a room back to the era it was built. A new cabinet, stone top, and modern faucets are the single biggest style upgrade in a bath short of a full remodel.
• Better storage. Older double vanities are mostly false drawer fronts and open bays. New cabinets add real soft-close drawers, drawer-within-drawer plumbing cutouts, and better organization.
• Right-sizing. Swapping a tired 60-inch unit for a 72-inch one where the wall allows, or moving from two cramped bowls to two comfortable ones with a center drawer stack.

The good news in every one of these cases: because the two-sink plumbing already lives in your wall, you get the transformation without the biggest cost driver of a two-sink layout.

Measure first: matching the new cabinet to the wall and the plumbing

Two numbers decide how smoothly this goes: the clear wall width and where your two drains and supply valves sit. Get both before you shop.

The wall run

Measure corner to corner, or to the nearest fixed obstacle — a shower wall, a door casing, a toilet clearance. Then buy a cabinet one to two inches narrower than that clear run so it slides in without scraping drywall or fighting an out-of-square corner. The two dominant double-vanity widths are:

• 60 inches — the workhorse size. Two bowls with a center drawer stack, comfortable on most master walls.
• 72 inches — real separation between the two stations and generous counter, the premium double footprint when the wall supports it.
• 48 and 84 inches — less common but available; 48 is tight for two bowls, 84 is a luxury run for a large master.

The two plumbing locations

This is the number people forget. Your existing double vanity has two drain stubs and two hot/cold supply valve pairs at fixed spots in the wall. When you pick a new cabinet, the two bowl locations should fall roughly over those existing stubs. Most standard 60 and 72-inch double vanities are built to common bowl spacing, so they line up — but a center-drawer cabinet that pushes the bowls farther outboard, or an offset-bowl design, can move a sink well off its old drain. Small offsets of an inch or two are absorbed by flexible supply lines and a little play in the P-trap; larger ones may need the plumber to add short branch extensions. Either way it's minor compared to a fresh rough-in, but it's worth confirming before the cabinet is bought.

One slab or two tops — and two faucets

Countertop

You have the same two paths as any double vanity. One continuous slab across both bowls — quartz or granite templated after the cabinet is set, with two undermount bowls — is what most homeowners picture and the most requested look. It adds a week or two of fabrication lead time and can't be ordered until the cabinet is in place. Two prefab tops are cheaper and available off the shelf, but they leave a seam or filler strip down the middle. For a master bath, the single slab almost always wins on looks; for a secondary or guest bath on a budget, two prefab tops are a perfectly honest choice.

Two faucets

A double vanity means two of everything at the sink: two faucets, two drain assemblies, and two sets of supply stops. Since the top is off during the swap anyway, this is the easy moment to put new faucets on both bowls — trying to reuse two old, worn faucets to save a small amount rarely pays off. Buy a matched pair so the bathroom reads as intentional, and confirm the faucet hole spacing (single-hole vs widespread) matches the new top before it's drilled or ordered.

How the replacement runs, start to finish

• Planning: Measure the wall, note the two drain and supply locations, choose cabinet width, top, and faucets. Confirm whether the jurisdiction needs any permit (a like-for-like swap usually does not).
• Demo: Shut off both supply pairs, disconnect two P-traps and two supply lines, free the old top, and pull the old cabinet. Inspect the exposed wall and floor for any hidden water damage while it's open.
• Set and level: Slide in the new cabinet and shim it dead level across its full length — the step that takes the most patience on a long box and a slab floor. Scribe and fasten it to the wall studs.
• Top: Install prefab tops now, or template a custom slab and install it on a return visit a week or two later. Set the two bowls.
• Connect: Mount both faucets, connect two drains and two supply pairs, caulk the top to the wall, and test both sinks for leaks and drainage.
• Finish: Rehang or replace mirrors and sconces, touch up any wall paint, and clean up.

A like-for-like swap with prefab tops is often a one to two-day job. A single custom slab stretches the calendar by the fabrication lead time, though the room is only fully out of service for part of it. If your existing setup is a single sink and you're actually adding a second, that's a different, bigger project — see replacing a single vanity with a double vanity, where the wall has to be opened for new plumbing.

What it costs in the Sacramento–Placer market (2026)

These are realistic estimate ranges for our service area, not quotes. A like-for-like double vanity replacement that reuses the existing plumbing locations generally runs $2,800 to $8,500 all-in. The line items behind that number:

• Double vanity cabinet: $700 – $3,500 depending on stock vs. semi-custom, width, and drawer configuration.
• Countertop (one custom slab, two undermount bowls): $900 – $3,000 for a 60–72-inch top, templated and installed — or roughly $350 – $1,100 for two prefab tops.
• Two faucets + two drains + supply stops: $250 – $900 for a matched pair.
• Demo and haul-away of the old vanity and top: $150 – $500.
• Plumbing connection (reuse existing stubs, two bowls): $300 – $900; more only if bowls sit well off the old drains and need short branch extensions.
• Set, level, scribe & install labor: $500 – $1,500, higher for a long 72-inch cabinet on an uneven slab.
• Mirrors and lighting (if replaced): $150 – $900.
• Minor wall patch and paint touch-up: $150 – $600.

For a broader look at how these pieces add up across different vanity types, see our dedicated guide on the cost to replace a bathroom vanity, and for the step-by-step on a straightforward swap, our how-to-replace-a-bathroom-vanity walkthrough.

What drives the price up or down

• Countertop choice. The biggest swing. A single custom slab costs more and adds lead time; two prefab tops keep it cheap and fast.
• Cabinet grade. Stock big-box boxes keep it low; semi-custom cabinets with soft-close drawers and a furniture-grade finish move the number up.
• Bowl alignment to old drains. A cabinet whose bowls land over the existing stubs connects fast; one that pushes bowls well outboard adds minor plumbing labor.
• Floor flatness. Sacramento slab-on-grade floors are rarely level, and a long cabinet needs careful shimming — more so at 72 inches than 60.
• Hidden damage. Old cultured-marble tops and worn faucets sometimes hide slow leaks; if the wall or subfloor under the old vanity is soft, repair adds cost while it's open.
• County. Placer County work (Roseville, Rocklin, Lincoln, Auburn) tends to run a touch higher on labor than parts of Sacramento County.

When to call a pro and getting an accurate estimate

A double vanity swap is more forgiving than a single-to-double conversion, but the two things most likely to trip up a DIY attempt are the same two things a pro handles quickly: leveling a long, heavy cabinet on an uneven slab, and connecting two sets of plumbing without leaks. A top that sits proud on one end or a P-trap that weeps behind the cabinet is the kind of small mistake that shows up weeks later. The reliable way to get a real number is a quick in-home look at the wall, the plumbing locations, and the floor.

Oakwood Remodeling Group is a 5.0★-rated, licensed bathroom-only remodeler based in Rocklin (CSLB #1125321), and we've replaced double vanities in bathrooms across Roseville, Sacramento, Rocklin, Auburn, Granite Bay, Folsom, and El Dorado Hills. This work is one piece of a broader bathroom vanity replacement scope and coordinates cleanly with new flooring, lighting, and the rest of a full bath remodel. Get a free in-home estimate and we'll measure the wall, check that your new cabinet will match the existing plumbing, and give you a straight range before any work begins.