Installing a new basin: Silicone seals the deal

September 22, 2012|By Mike McClintock, Special to Tribune Newspapers
  • With modern, flexible water connections, you don't need to solder a network of copper underneath the sink.
With modern, flexible water connections, you don't need to solder a network of copper underneath the sink. (Mike McClintock photo)

Installing plumbing fixtures is usually left to contractors. But upgrades like a new kitchen sink are DIY doable. The best candidate is a self-rimming model. The basin section fits through a hole in the counter and a surrounding lip rests in a bed of silicone on the counter. And with modern, flexible water connections, you don't need to solder a network of connected copper underneath.

Tools and materials. You'll need two wrenches for the water lines. If one of those is a pair of large, slip-joint pliers, that will also handle the drain line. An elongated faucet wrench will reach up into the narrow space between the back of the sink and the cabinet. But the better approach is to turn off the supplies, disconnect the water lines at the cutoffs, and pull the faucet with the sink. The same goes for the opposite direction. Make all the faucet and drain basket connections on the sink before it's set in the counter. That will include thread-sealing tape at the plumbing connections, a tube of 100 percent silicone to waterproof the rim and a screwdriver to tighten clips that usually come with the sink and secure it to the counter. This project stretches DIY boundaries if the new sink is larger. Then you would need tools to alter the countertop — like a tile saw or nipper — and a jigsaw to enlarge the hole through supporting plywood.

Connecting the faucet and drain basket. Most faucets come with a mounting plate and concealed gasket that does not require a silicone seal. Many drain baskets do not come with a gasket. Check the manufacturer's instructions — some recommend silicone and others plumbers putty. For DIYers, silicone is usually easier. Make a small, angled snip at the end of the tube, apply consistent pressure on the handle and keep the tube moving at a steady pace. With plumber's putty you have to form an even roll to make what's basically a sculpture of a gasket.

Setting the sink. Start by setting the sink dry; no silicone. Then check underneath, slide a couple of clips into the channels inside the lip and see how they will grab the plywood counter. Centering the sink usually works best — so the clips apply even pressure and don't fall short or just barely grip the wood on one side. Measure or mark that position on the counter surface. Then, while it's still upside down, spread a continuous bead of silicone along the bottom edge of the self-rimming lip. When you set the sink and tighten the clips some silicone should ooze out. It's better to apply too much than leave a gap where water can seep into the cabinet. To finish, connect the new water lines to the existing cutoffs and the basket tailpipe to the drain and trap.

Using silicone. There are many videos and step-by-step instructions for this project on the Internet. Beware. For instance, I found a couple that say set the sink, tighten the clips, then run a bead of silicone between the sink and the counter. That will look great, right? Nice tile or maybe granite, a sleek edge of stainless steel, and in the middle a bead of silicone that won't stop leaks because it's on top of, instead of in, the joint. But it will stand out, look ugly and foster mold. The other brainless suggestion is to wipe away any excess silicone immediately. Can't be done. The silicone simply spreads and sticks to everything. It's not like a latex caulk that you can finish with a wet finger. The drill is to let it set at least an hour, then trim exposed material with a sharp knife or razor and peel away the excess.