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.
Before you begin, you have to decide on what vessel or countertop sink you plan on using. If you want to leave the existing countertop in place and retrofit a new sink, then the size of the sink must fit with the existing usable space. An important consideration for this is understanding the location of the faucet as well as the height of the spout. Can you fit both in the space that is allocated?
If not, as is often the case, then you need to replace your countertop countertop. A vessel sink installation requires holes in the vanity top or countertop for the sink drain and faucet, if it is a deck-mount type. The hole for the sink and (deck-mounted) faucet must be coordinated and drilled in the proper location for an aesthetically pleasing look and for functionality. Most if not all vessel or CTP sinks come with a template that gives you a precise layout for cutting the hole. This and the holes for the faucet should be cut by someone with professional experience, especially if the countertop is made of natural stone, engineered stone, or cultured marble.
The faucet must be a high-spout type, unless you want to opt for the more complicated process of opening the wall to install a wall-mounted faucet. A deck-mount faucet is much easier to install before the sink is in place.
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 has 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.
Equipment / Tools
- Tongue-and-groove pliers
- Hacksaw (as needed)
- Drain fitting and tailpiece
- Plumber's putty
- Pipe-joint compound
- Drain trap assembly (1 1/4-inch or 1 1/2-inch, as needed)
Position the Sink
Position the sink on the countertop. The sink may come with a mounting ring or gasket to be used between the sink and the countertop. If your sink has one, position the mounting ring over the drain opening and set the vessel on the ring. Other sink models may call for a bead of silicone caulk to seal the sink to the countertop.
Insert the Drain Flange and Tailpiece
Apply 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 tailpiece end of the drain fitting down into the sink drain opening and through the cutout in 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.
Note: It is best to install the drain onto the sink prior to setting it in place.
Secure the Tailpiece
Apply pipe joint compound to the rubber seal. Working from underneath the sink, slide the seal up around the drain tailpiece and into the countertop cutout as far as it will go. Thread the friction ring onto the tailpiece, followed by the mounting nut. Hand-tighten the mounting nut as far as you can, then tighten it just a bit more with tongue-and-groove pliers. 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. Wipe away excess plumber's putty from around the drain flange with a rag.
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.
Complete the Drain Assembly
Connect the P-trap to the sink drain tailpiece, using a slip nut and washer, making it just snug for now. Install a trap arm between the P-trap outlet and the branch drain pipe in the wall or floor, using slip nuts. The trap arm must have a slight downward slope toward the drain line. Depending on the drain configuration and the location of the branch drain opening, you may need to add a tailpiece extension and/or cut the trap arm to fit, using a hacksaw.
Double-check the fit of all the drain parts, then tighten the slip nuts further by hand or with tongue-and-groove pliers. Many slip nuts don't require pliers. Be careful not to over-tighten the nuts.
If the drain tailpiece is 1 1/4-inch and the P-trap is 1 1/2-inch, connect the trap with a reducer fitting.
Test for Leaks
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 to give it a good volume test. Slight leaks at the slip nuts can usually be fixed by simply tightening the slip 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 the drain and start over, focusing on getting the drain fitting properly sealed in the sink's drain opening.