A RIM WITH NO GAPS. A carefully installed sink’s rim will rest firmly and evenly on top of the countertop, with no gaps.
If you are replacing an existing sink, remove it: Unplug the garbage disposal, disconnect the dishwasher hose, and unscrew one or more nuts on the trap. If it is stainless steel, remove the clips (see Step 11); if it is cast iron, cut through the bead of caulk around the rim. Then lift it out carefully, watching for any connections you missed. If you plan on keeping the countertop, choose a sink that fits into the existing hole.
If you are installing a new countertop (as shown in this sequence), position the sink above a “sink base” cabinet, which allows room for the sink. Measure to be sure the sink will fit, preferably with several inches to spare. There should be a drain line and supply stop valves nearby in the wall.
1. MARK FOR THE OPENING. Measure carefully and position the sink, upside down, where it will go. Usually, the front lip is 1½ in. to 3 in. from the front edge and centered over the base cabinet below. Apply a few pieces of tape to keep the sink from moving and scribe a pencil line around the lip. This is not the cutline!Next, mark the actual cutline, which is 3⁄8 in. to 1 in. inside the outer line (above). The easiest way to do this is to offset the sink the appropriate distance and use the edge of it as a template, as shown; you will need to shift its position to scribe the other two sides.
2. FOUR STARTER HOLES. Erase or at least blur the outside line to be sure you don’t follow it. At each corner of the inside line, bore a starter hole, about ½ in. or ¾ in. wide.
TIP: To make absolutely sure a laminate countertop will not chip, some remodelers turn the countertop upside down and cut with a circular saw. Of course, this complicates things.
3. CUT THE HOLE. Make a simple 2×4 support to keep the cutout from falling when you finish the cut (top). (If it does fall, it can seriously chip the laminate.)Equip your jigsaw with a fine-cutting blade and place tape all around the cut hole. Press down firmly as you make the cut; watch to be sure you are not producing large chips that go outside the outer line. If you are, switch to a finer cutting blade.
Cutting a Solid Countertop
If you have granite, quartz, or solid-surface, you can cut it using a grinder equipped with a diamond blade. Cut slowly and stop periodically to check that you are not overheating the blade. If the blade gets very hot, gently spritz it with water, taking care that the water does not splash up onto the grinder itself.
4. INSERT THE BASKET STRAINER. In our example, one of the holes has a simple basket strainer, whereas the other has a mounting bracket for the garbage disposal. To install a basket strainer, roll out a rope of plumber’s putty and wrap it around the bottom of the strainer’s flange.With the sink right side up, press the strainer into place; some putty should squeeze out. Do the same for the mounting bracket in the other hole.
TIP: It will save trouble if you install as many parts as possible—the strainers, the disposal, the faucet, and the trap—with the sink upside down and resting on the counter or a pair of sawhorses. Use a drop cloth to protect the counter from scratches.
5. TIGHTEN THE STRAINER NUT. Turn the sink upside down. Gently (so as not to move the flange while you work) slip on the rubber washer, then the cardboard washer. Screw on the mounting nut. Hold the strainer in place with a pair of locking longnose pliers and tighten the nut with a spud wrench. Check the other side to see that the flange is centered in the hole.
6. MOUNT THE DISPOSAL BRACKET. At the hole for the garbage disposal, slip on the cardboard gasket, the backup ring, the ring with the three screws, and the mounting ring. (This will be easier than doing it upside down inside a cabinet, but it is still a bit tricky to get the ring on.) Again, check the inside of the bowl to see that the flange is centered on the hole before the final tightening.
If There Is No Disposal
If you have no garbage disposal, here is a very simple trap configuration for a double-bowl sink, where both bowls share a single trap. However, codes in some areas require that each bowl have its own trap.
7. INSTALL THE FAUCET. Installing the faucet should be simple with the sink upside down. Follow the instructions provided by the manufacturer, as faucet mounting procedures can vary.
Boring a Mounting Hole
Most sinks come with holes predrilled for faucets and accessories, but if you need to cut a hole in your stainless-steel sink, it is usually not difficult. In most cases, a bi-metal hole saw, as shown, will do the trick. (If your sink is very thick and hard, you may need a titanium step drill bit.) The hole size is usually 1-3⁄8 in. Determine the center of the hole, and tap with a hammer and nail set to create an indentation so the pilot bit will not wander. Then drill the hole, squirting oil on the bit regularly. Take your time; it may take 5 or 10 minutes to make the hole. If the bit heats up and starts to smoke, stop and let it cool off. If the finished hole is rough around the edges, deburr it with a file or sandpaper before installing your new faucet.
8. START ASSEMBLING THE TRAP. Install the garbage disposal. In this setup, the trap’s tailpiece goes down from the basket strainer and has a T fitting for fastening to the disposal. Cut the tailpiece so the T is directly opposite the disposal’s outlet, and install the T. Measure another tailpiece for cutting, and cut with a hacksaw or a miter saw.At the disposal’s outlet, insert the rubber washer and attach with the diamond-shaped large washer and two nuts.
9. COMPLETE THE TRAP. Measure the height of the trap adapter in the wall and assemble a trap that will reach into it. Here, the disposal and the other bowl share a single trap; some codes may require separate traps for each.
10. SEAL THE RIM. Seal the underside of the rim so water cannot seep underneath. This can be done with silicone caulk, but some sinks come with foam strips, which are less messy and make a surer seal. Pull off the paper backing as you press the strip into place.
11. STAINLESS-STEEL CLIPS. The sink should come with mounting clips. Slip them into the flange around the bowl and slide them so they are evenly spaced (top). Turn the clips so they do not get in the way, and carefully set the sink in place.From underneath, turn the clips and tighten them with a screwdriver (above) to firmly fasten the sink to the countertop.
Setting a Cast-Iron Sink
Cast-iron sinks are heavy, so they need no mounting clips. Just set the sink in place, make sure there are no gaps, and apply a bead of silicone or “tile and kitchen” caulk around the rim.
Excerpted from Plumbing (The Taunton Press, 2016) by Steve Cory.
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