Home Remodeling: Replacing a Bathroom Vanity and Sink

Installing a bathroom vanity should not be too difficult as long as you do not need to modify the walls, flooring, or make significant changes in the existing plumbing. Most people will install a bathroom vanity as part of an upgrade to the space. This means that a vanity is removed, and another one is inserted into the opening. Removing the old vanity can be a big job if you are not a plumber or carpenter. By following a few simple steps, most people with decent do-it-yourself skills should be able to master this project with a few hours of labor.

Start the project inside the existing vanity.

Open the doors of the vanity and locate the cutoff valves that are between the income water lines and the riser tubes going to the faucet set. Turn these valves off to stop the water flow to the vanity. Confirm that the valves have worked by turning on both the hot and cold water faucets. If a stream of water does come flowing out, the water is off. If there are no cutoff valves or the water still runs, locate the master cutoff valve for the house or go to the water meter to turn off all of the water to the house. Once you have successfully turned off the water, it is time to disconnect the plumbing from the vanity.

Using the correct size wrench, loosen the nuts that hold the riser tubes to the income water line or cutoff valves.

It is a good idea to place a small bowl beneath the connection to catch any water that may drip from the riser tubes. Locate the last drain joint before you reach the bottom of the sink. Use a pipe wrench to loosen the large nut. Sometimes, these can be turned without a wrench by just gripping it and turning.

With the plumbing disconnected, it is time to remove the sink from the vanity.

Look at the underside of the vanity to see if it has fasteners holding it to the vanity base. If there are fasteners, remove them before attempting to move the top. Most vanity tops just sit on top of the base and depend on the weight of the top and plumbing connections to do most of the work to hold it in place. Sometimes caulk is placed under the top to help anchor it. You will probably see a bead of caulk or sealant going along where the top adjoins to the wall. Be careful loosening the top from the wall so that the wall is not damaged.

Tap the vanity top gently to loosen if from the top of the base and wall.

Once the top is loose, lift it up and out of the base. If you intend to reuse or sell the faucet set, take care when setting the top down. With the top out of the way, look into the vanity base and locate the screws that attach it to the wall. Use a screwdriver to remove the screws to allow you to remove the vanity base. Notice how the plumbing enters the base. It may come from the floor or through the back or a combination.

Disconnect any additional plumbing necessary to be able to remove the vanity base.

Once you have moved the old base, make any adjustments to the plumbing that may be needed before installing the new vanity. Also, check to see if there are any modifications that need to be done to the new vanity to allow the plumbing to enter it. On some units, you may need to cut small openings into the back or floor of the base to allow the pipes to enter and exit.

Carefully lift the new vanity base into position into the space where it will be installed.

As you lift the vanity into place, thread the plumbing through the openings in the cabinet so that they can be accessed from inside the vanity when you install the drain and faucets. Make any adjustments necessary to level the vanity. This may require the use of shims if the floor underneath the cabinet is not even. Once the vanity is levelled and sits solidly against the back wall, use screws and fasten it to the wall. Make sure that the screws pierce the wall covering and screw into the studs inside the wall. Often, this requires screws two inches in length.

Attach the faucet set to the vanity top.

Whether you are using a vanity top with a built in sink or will be attaching a sink to the top, the faucet set generally still attaches to the vanity top. Remove any nuts, washers, and spacers that may be attached to the faucet set. Slip the water entry ports of the faucet through the holes in the vanity top so that the protrude through the bottom. Following the faucet manufacturer’s directions, use the supplied hardware to affix the faucet set to the unit.

Install the riser tubes at this time.

Once the faucets are in place, screw the connectors of the riser tubes onto the inlet ports on the faucet. It is a good idea to use some Teflon plumbers tape around the threads to assure a tight fit that does not leak. Snug the fittings up on the faucet ports. Most of these are designed so that you can firmly tighten them by hand. If you are not sure, use a wrench gently to give each connector a half turn or so. Most of the time you are dealing with plastic threads on one or both parts of the connection. So, too much force can ruin the threads.

Attach the sink and drain tube next.

Because so many variations exist on sinks for vanities, follow the directions for the sink that you purchased for the proper installation technique. Some sinks will attach on top of the vanity. Others will fasten underneath. Whether you have a vanity top with a built in sink or had to attach the sink to it, you will still have to install the drain into the sink basin. Coat the ring where the drain will attach inside the sink with a thin layer of plumbers putty. Seat the gasket onto the putty and push the drain tube through the gasket and drain hole until the metal or plastic ring that houses the stopper sits firmly against the bottom of the sink.

Fasten the drain to the sink with the hardware that has been provided.

Every sink drain comes as a kit to be installed. This includes a nut and gasket that goes on the drain tube from under the sink. Screw the nut up until it is snug to the sink. You can tighten it more later if the drain leaks. You are now ready to set the top onto the vanity base.

Make sure that the top will be stable resting on the vanity.

Some vanity tops come with fasteners to use to anchor the top to the base. Other depend on a combination of the weight of the top and some type of caulk or adhesive to hold the top in place. If you need to use adhesive, put a bead of the material all of the way around the upper edge of the vanity base before setting the top on it.

With the vanity top attached to the base, it is time to complete the plumbing.

Attach each riser tube to the proper water source. One is hot, and one is cold. You want the cold water to attach to the right side of the faucets as you face the sink from the front of the vanity. Use a wrench to make sure that the connection to the water source is tight. Use appropriate sized drain tube to make the connection to the sink drain.

You will need to install a J-trap under the sink to keep sewer gas out of your house.

Use the gaskets and nuts provided with the fittings to make the attachments. Make sure that gaskets are slipped onto the drains with the tapered edge pointing toward the connection. If you have the pull and push type of drain stopper, install the hardware to connect the knob on the faucet set to the lever that opens and closes the drain.

Test your work.

Turn on the water cutoff valves and open the faucets a little to let water fill the tubes and check for leaks. Turn off the faucets to let the water pressure build so that any leaks will appear. If you find leaks, tighten the fittings until the leak stops. Stop the sink and and put a few inches of water into it. Check underneath for leaks where the drain fastens to the sink. Open the drain and let the water flow out. Look for leaks in the rest of the drain plumbing. Tighten any joints that leak to resolved the leaks.

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