Installing Sinks ; Self-rimming and Recessed

Whether installing a bathroom sink or a kitchen sink, the procedure is basically the same.

There are three basic types of counter sinks used in bathrooms and kitchens:

  • Self-rimming drop-in sinks with clamps. This type sink is very common in stainless steel double sink or single sink models for kitchen use, and porcelain or stainless steel for bathroom use. Self-rimming drop-in sinks feature a “rim” or lip around the perimeter. They drop into a pre-cut hole in the counter top so that the rim rests directly on the counter top, and are fastened in place using special clamps below. Caulking is applied around the rim to provide a water seal; or plumber’s putty is used under the rim.
  • Self-rimming drop-in sinks without clamps. This type sink is simply dropped into the opening so that the rim rests on the counter top; clamping underneath is not necessary. Usually porcelain or ceramic, they are held in place with a bead of caulking around the rim. This holds it to the counter top and provides a water seal.
  • Recessed or undermount sinks. This type sink rests on a plywood base under the counter top level, creating a seamless flow. It is popular for ceramic tile, natural stone, or other solid type material countertop, but should not be used with those made from laminate. This is because of inevitable “bubbling” that will happen due to condensation that has seeped underneath. Ceramic/porcelain or cast iron is favored over stainless steel; due largely to the difference in expansion and contraction properties. In some cases, double-walled stainless steel is acceptable.


Before you Begin

The first step in any sink removal/installation is shutting off the water supply. If the water supply lines under the sink do not have shut-off valves on them, now is a good time to have some installed.

Reasonably priced, high-quality flexible vinyl hose kits are available in most hardware or building supply centers. Be sure to size fittings accurately for both the supply lines and faucet fixtures. Installing shut-off valves in supply lines will make future sink installation and maintenance easier and handier. It will also provide quick access for emergency shut-off.

Sink Replacement – Same Size as Old

If you are replacing an old sink with a new one into an existing counter top opening, you will need to install one that is the exact same size as the old.

After removing the old sink, check the counter top for any water damage and rot. If any is detected, make necessary repairs. If the extent of damage warrants it, replace the old counter top with a new one.

Follow these steps for installing the sink:

  1. Use denatured alcohol or mineral sprits and a clean rag to cleanse the counter top around the opening. Also clean the underside of the new sink’s rim to prepare it for caulk or plumber’s putty.
  2. To install the new sink, simply drop it into the opening; make sure it fits with no gaps. For clamping sinks, apply a thin ¼-inch bead of plumber’s putty or caulk under the rim around the opening to provide a water seal. Once the sink is aligned and clamped firmly into place, clean off excess caulk or putty with the rag.
  3. Install the faucet and connect the supply lines. Connect drains, using a ¼-inch bead of plumber’s putty beneath the rim of the drain assembly; press it into the opening. Screw the tightening rim on the assembly from underneath, and tighten with a wrench. Attach and tighten drain fittings.
  4. Check supply lines and drain pipes for leakage. Monitor closely until you are sure there are no leaks. Even a slow drip left unattended will wreck havoc under your sink cabinet.

Installing a Sink in a Countertop for the First Time

If you are installing a sink for the first time into the counter top, it is necessary to take careful measurements for proper placement of the sink and opening. Be sure to leave at least 1 ½ inches, but not more than 3-inches from the edge of the counter.

Once you are sure of placement, place the sink upside down on the counter top, and mark around the perimeter of the rim. Be sure that the edge of the rim is parallel to the edge of the counter top. Remove the sink, and mark a second line about 1½-inches inside the first mark. Note: if another measurement is specified in manufacturer’s instructions for any given sink, use that one instead.

Since a jigsaw (reciprocating saber saw) is used to cut along the inside mark, you will need to drill a hole just inside of the inside line at each corner big enough to insert the saw blade. It is best to put masking tape on the bottom of the saw to avoid scratching or other damage to the counter top.

Cut carefully, staying on the line. Do not allow the saw to wander off of the line. When the hole is finished, insert the sink, and check the fit. Make sure the sink is properly aligned.

Self rimming sinks without clamps are dropped into the opening and caulked into place. Finish installation following the 4 steps previously listed.

Recessed or undermount sinks are installed to the bottom side of the counter top before the counter top is installed. This type recessed sink/countertop arrangement is readily available in a variety of pre-manufactured kits; the sink and pre-cut counter top come ready to assemble. Some kits even come with the sink already installed.

Caulk the edge of the sink, and put it into place. Screw it down using the hardware that came with the sink, following manufacturer guidelines. Once the sink is in place, the countertop installed and sink faucets attached and secured, follow previously listed steps 3 and 4 to connect supply lines and drain.

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