How to Upgrade to a Double-Single Vanity

Changing a one-sink bathroom vanity into a double-sink vanity can go one of two ways. You can add a second sink to your existing vanity or install a new vanity with two sinks. Assuming your vanity is large enough, installing an additional sink can be labor extensive and calls for above-average carpentry and plumbing skills. This may be a project best left to the pros. If you’re an average DIYer, installing a new vanity with double sinks can be less challenging—and it’s a great way to update your bathroom. 

How to Get the Ideal Fit for a New Double-Sink Vanity

Before you hop online and check out your next double-sink vanity, you’ll need to know a few measurements. Plan on a minimum of 30 inches between your new vanity and other fixtures like a toilet or tub. Typically, you want the two sink basins to be no less than 30 inches apart, and each basin should be at least a foot from a wall. This maximum allows for two sinks to share a single waste line. However, separate traps and drains may be required if a vanity has full-length drawers. 


Additionally, measure how much room your bathroom, closet, and shower doors need to open fully. It’s also a good idea to check with your local building department for codes or other regulations for your project, so you save time and money. Once you have your measurements, you can calculate the size of the vanity you’ll install. Now you can jump online and head to your local home improvement store to pick out your new double-sink vanity. 

How to Replace a Single-Sink Vanity With a Double-Sink Vanity

Removing and installing a vanity is a project many DIYers can tackle as long as they have some basic plumbing and carpentry skills. If you aren’t confident in your plumbing skills, consider handling the carpentry end of the project and letting a pro ensure your plumbing is up to code. The last thing you want is to spend a weekend putting in your new double-sink vanity and running into a last-minute plumbing issue. 

Removing a Single-Sink Vanity

Before installing your two-sink vanity, you must remove the old one. Take your time and work slowly to avoid damaging walls, plumbing, and other areas. You’ll only need a towel, 

drill, adjustable wrench, bucket, and utility knife.


  • Turn off the water supply.
  • Open the faucets to remove the remaining water.  
  • Put a bucket under the plumbing to catch water. 
  • Loosen the nut at the top of the P-trap with an adjustable wrench.
  • Use the adjustable wrench to disconnect the water supply lines. 
  • Cut the sealant at the backsplash with a utility knife. 
  • Remove any screws that secure the vanity to the wall.
  • Carefully pull the vanity away from the wall to ensure it is detached.
  • Remove more screws or sealant If the vanity doesn’t come away from the wall easily.
  • Use a towel to wipe up excess water.

If your old vanity doesn’t fit through the door with the vanity top intact, you’ll have to remove the vanity top. Most vanity tops are secured with glue and screws, so a drill and crowbar should get the job done quickly. Before installing your new double-sink vanity, remove the old one and any debris, so you’ll have plenty of room to work. 


Installing a Double-Sink Vanity

Installing a two-sink vanity in your bathroom is not quite the reverse of removing a single-sink vanity. You have double the plumbing, and you’re fitting a larger vanity, so use this step-by-step guide for a successful installation.


Here’s what you’ll need to complete the job:


  • Stud finder
  • Pencil
  • Level
  • 3″ cabinet screws
  • Drill
  • Caulk
  • Water supply lines, P-traps, shut-off valves, and shut-off valves
  • Pipe thread sealant
  • Adjustable wrench
  • Basin wrench


Depending on the vanity, your new double-sink setup may come with the vanity top uninstalled. If this is the case, you’ll need to attach the vanity top following the manufacturer’s instructions after installing the vanity cabinet. Here’s how to install a bathroom vanity with professional-looking results:


  • Use a stud finder to locate the wall studs behind the drywall. Mark the location of each stud with a pencil.
  • Lift the vanity cabinet into place against the wall. 
  • Use a level to ensure the vanity cabinet is level, and adjust the base or legs as needed with shims. 
  • Once the vanity cabinet is level, use screws to attach the cabinet to the wall studs. 
  • Ensure the back of the vanity is flush with the wall and apply caulk.
  • Use a basin wrench and adjustable wrench to install the faucets onto the sink.
  • Attach the drain assembly to the sink and secure it with pipe thread sealant.
  • Attach the P-traps to the sink drain pipes and the water supply lines to the faucet with a wrench.
  • Turn on the water, check for leaks, and use the wrench to tighten the connections if needed.


Complete your project by removing excess caulk, clearing out debris, and wiping everything down for a sparkling shine. 


Depending on your DIY skill levels, removing a single-sink vanity and replacing it with an updated two-sink version should take only a weekend or so. When you begin the project, check off all the necessary tools and supplies and have everything handy so things run smoothly. When you’re done, pat yourself on the back and admire your handiwork. By the way, since you did all the work, you can choose which sink is yours!

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