A vessel sink—which sits on top of a counter, vanity, or any adapted cabinet—can give a bathroom a uniquely polished look. The top of the vanity can be granite, tile, laminate, or any other type of solid surface. Vessel sinks also give you the option of converting a dresser or other piece of furniture into a sink vanity, creating a look that is truly unique.
Drain holes and faucet holes will have to be drilled on any vanity or dresser top chosen for a vessel sink installation. Other considerations are the drain pipe location and countertop height. Setting a vessel sink on top of a standard height vanity results in a sink that is much too high. The height of the vanity needs to be low enough so that the installed sink height is somewhere between 30 to 36 inches.
Also, keep in mind that if you will be using a piece of furniture that is not specifically designed for a vessel sink, additional alterations may have to be made. These may include removing and disassembling drawers, then attaching only the drawer faces onto the cabinet to allow room for water and drain lines inside. And the back of the dresser will most likely have to be opened to accommodate the water and drain lines. If you are installing a vessel faucet as well as a vessel sink, you should install the faucet first. It is considerably more difficult to install the faucet after the sink is already in place.
Check the vessel sink you plan to install, as it may come with special mounting instructions. Most installations follow a similar process.
Tools and Supplies You Will Need
Most vessel sinks come with a drain fitting for the bottom of the sink, but if you are buying this separately, choose one designed for vessel sinks.
Before you begin, make sure you have the correct drain fitting for your vessel sink drain. In most installations, this fittings serves both as the drain opening as well as the anchoring mechanism that holds the sink in place on the countertop. If the sink you purchased as an overflow passage built into it, make sure your drain fitting also has an overflow. Similarly, a sink without an overflow will require a drain fitting without an overflow. Note that glass vessel sinks usually require a mounting ring that sits on the counter and holds the vessel.
Position the Sink
Begin by positioning the sink on the countertop or cabinet. If the bottom of the sink is flat, then you can usually mount the vessel directly onto the countertop, aligning it with the drain opening.
The vessel sink may come with a mounting ring or gasket to be used between the sink and the countertop. Mounting rings come in many finishes to match your faucet trim. Position the mounting ring over the drain opening and set the vessel on the ring.
Having a helper to hold the vessel sink in place as you attach the drain fitting is a good idea, particularly if it is a round-bottom vessel. If you don’t have a second set of hands, carefully hold the vessel with one hand while you attach the drain fitting.
Attach the Drain Fitting
The drain fitting for a vessel sink is slightly different than standard drain fittings. It includes a strainer assembly with a threaded tailpiece that inserts down through the sink drain opening and countertop opening, a rubber seal that slides up around the tailpiece from beneath the countertop, and a friction ring and mounting nut that are tightened down around the tailpiece to hold the drain assembly and sink firmly in place.
Begin by applying a bead of plumber's putty along the bottom surface of the drain flange on the drain fitting. Or, if the drain comes with a foam or rubber gasket, place this against the bottom surface of the drain flange.
Insert the threaded tailpiece on the drain fitting down into the sink drain opening and through the cutout on the countertop. If the drain flange has lettering on it, position it so the lettering reads upright when looking down into the sink from the front.
From below the sink, apply pipe joint compound to the rubber seal, then slide it up around the drain tailpiece and into the countertop cutout as far as you can. After the seal is in place, thread the friction ring, then the mounting nut, onto the drain tailpiece. Hand-tighten the mounting nut as far as you can, then tighten it just a bit further with channel-lock pliers or a pipe wrench. Be careful not to over-tighten, as this can damage the sink. Check the alignment of the drain fitting and lettering once again to make sure it is still straight.
Connect the Drain Trap
Now that the vessel sink drain is installed and secure, you can connect the drain trap to the sink's drain fitting. Here, installation proceeds just as for installing any drain trap. The 1 1/4-inch drain tailpiece coming from the vessel sink can fit onto a 1 1/2-inch trap using a reducing fitting.
A drain trap consists of a trap bend that fits onto the drain tailpiece of the sink, plus a trap arm that connects the other half of the trap bend to the branch drain opening in the wall. Connections are made with slip nuts and beveled slip washers. Depending on measurements, extension pipes may also be needed to extend the drain tailpiece to the necessary height or to extend the trap arm to reach the branch drain opening.
Test for Leaks
After all of the connections are made, test the drain thoroughly for leaks. First, run water into the sink and check for leaks under the sink. If there are no leaks under normal running conditions, fill the sink all the way up, so you give it a good volume test. Slight leaks at the slip nuts can usually be fixed by simply tightening the slips nuts just a bit further. However, if there is leaking around the bottom of the sink onto the countertop or around the rubber seal, it indicates that the drain fitting is not properly seated in the bottom of the sink. In this case, you'll need to disassemble and start over, focusing on getting the drain fitting properly sealed in the sink's drain opening.