How to Plumb a Pedestal Sink

We show you every gritty step—start to finish

Pedestal sinks present unique challenges

Replacing your old vanity cabinet with a pedestal sink is one of the quickest and easiest ways to remodel a bathroom (Photo). But we should warn you—pedestal sinks can be tricky to put in, even for pros. Often the pipes aren't in the right spot, making it difficult to fit the pedestal in place and connect the pipes so they look nice. You may discover that there's no floor tile underneath the vanity cabinet so you'll have to patch or replace the floor. And you may also have to patch missing baseboard.

In the following article, we'll show you how to handle the most common problems, including how to relocate your drain and water pipes for a neater installation.

You'll be able to install a new pedestal sink and faucet in a day even with no previous experience. If you have to relocate the pipes, plan to spend a few more days to move the pipes and patch and paint the wall. For this you'll need basic plumbing skills like soldering copper and cutting and gluing plastic pipe.

For a complete listing of the tools and materials you'll need, see “Tools and Supplies” below. And be sure to contact your building inspections department to see whether a permit is required for this plumbing work.

Tools and supplies

Tools:
Adjustable wrenches
Large slip joint pliers
Hacksaw with fine-tooth blade
Close-quarters tubing cutter
Tubing cutter
Drill and bits
5/16-in. masonry bit
Tape measure
2-ft. level

Soldering tools and supplies:
Propane or Mapp gas tank with regulator
Lead-free solder
Flux
Wire brush for 1/2-in. fittings
Emery cloth
Heat shield cloth
Leather gloves
10-ft. length of 1/2-in. copper pipe
1/2-in. copper elbows, couplings and caps

PVC pipe tools and supplies:
Fine-tooth saw
PVC glue
PVC primer
1-1/2 in. PVC pipe
PVC 45- or 90-degree elbows
PVC sanitary tee
Transition couplings
Organic vapor respirator

Other tools:
Reciprocating saw and metal-cutting blade
Circular saw
Drywall keyhole saw

Note: You can download a copy of this list from the Additional information below.

Back to Top

Step 1: Tear out the old vanity

Tear out the old sink and vanity (Photo 1) and check the drain and supply pipe locations. Pedestal sinks look best if the drain and supply pipes are centered and partially hidden by the sink. Your new sink will come with wall measurements showing ideal plumbing locations.

To be absolutely sure, position the pedestal sink and loosely install your new faucet, pop-up drain and P-trap. Now measure from the floor to find the drain height and determine the best location to put the water supply valves mostly out of sight. Our old drain was 6 in. off center and a few inches too low. The water pipes also were in the wrong spot.

Pedestal sinks look best if you shift the plumbing. If you have to relocate pipes, start by removing a section of wall covering wide enough so you can move the pipes and install wood backing (Photo 2). This means wall repair and repainting later. Use a keyhole saw to cut the drywall (Photo 2), but keep the saw blade shallow to avoid hitting wiring or pipes.

Tip: It's easier to cut along the edge of the studs and add 2x2 drywall nailers alongside the studs later than to try to cut down the middle of the studs.

Back to Top

Step 2: Replumb the drain and water supply pipes

Cutting steel pipes like ours is a real chore with a hacksaw. Rent or borrow a reciprocating saw (Photo 3) to speed up the job. Plastic pipes are easy to cut with any fine-tooth saw. To connect PVC (white) plastic drainpipes to either ABS (black) plastic, copper or steel, use transition couplings (Photo 5). Transition couplings have a rubber gasket surrounded by a steel sleeve with screw clamps at each end. Don't confuse them with the solid rubber or rippled steel collar types. Transition couplings are available at home centers and plumbing supply stores. Match the transition coupling to the pipe size. If your old pipes are PVC, then you're set to go; just prime them and glue the new PVC fittings on.

Plastic pipe makes quick work of relocating your drain. Cut and assemble the drain and vent pipes as shown in Photos 5 and 6. Don't worry if you make a mistake; it's easy to fix. Just cut the pipe and join a new section with a PVC coupling.

Begin by clamping elbows to the transition couplings on the drain and vent pipes. Then start at the drain and work up toward the sanitary tee, making sure to center the sanitary tee on the new sink location and at the right height. Complete the drain by flexing the PVC drain assembly just enough to glue in the last section of pipe (Photo 6).

We've run both the drain and vent pipes at a 45-degree angle for optimal performance. If you're moving the pipes very far, you might have to use 90-degree elbows instead. Keep in mind that your vent pipe shouldn't run horizontally unless it's at least 6 in. above the “spill line” of the sink, or about 42 in. above the floor. Leave the drain stub unglued until the drywall is finished. Then cut the stub so the trap adapter fits snug to the drywall and glue them all together (shown completed in Photo 10).

To secure the copper pipes and help hold them in place as you solder them, level and screw a scrap of wood between the studs and mark the pipe locations on it. Cut the copper pipe and solder the fittings together (Photo 7). Leave about 6 in. of copper pipe sticking out and solder on a cap so you can turn the water on to test for leaks. When the wall patching and painting is done, install the new shutoff valves (Photo 10).

Screw wood backing to the studs to support the edges of the drywall (Photo 8). Measure the sink for the location of the anchors and screw wood backing between the studs in this area (Photo 8). If your work requires a permit, call for a plumbing inspection before closing the wall.

Back to Top

Step 3: Install the new sink

With the prep work done, you can mount the sink in about three hours. Here's how. First, install the valves, drain stub and sink mounting bolts (Photos 10 – 12). Next follow the faucet directions to install the faucet and pop-up drain on the sink (Photos 13 and 14). Finally, mount the sink and connect the plumbing (Photos 15 – 17).

When you set the sink on the pedestal to mark the mounting holes, don't be surprised if it's a little tippy—they're not always perfect. Slide plastic shims under the pedestal if necessary to keep it from rocking, and stick foam pads or rubber cabinet door bumpers under the sink bowl to level it before marking the wall and floor for the mounting screws (Photo 11). When the installation is done, fill the gaps at the floor and between the pedestal and bowl with silicone caulk that matches the sink.

Making the final connection between the faucet and valve can be tricky. If you're having trouble fitting the supply tube into the valve (Photo 16), loosen the valve (reverse the procedure shown in Photo 10) and swivel it to allow clearance to insert the tube. Then retighten the connection. Always use two wrenches to tighten compression fittings, one to hold the valve and the other to tighten the nut.

Complete the sink installation by installing the P-trap assembly (Photo 17). Hand-tighten the slip joints. Then give them an extra quarter turn with a large slip joint pliers. This is a tight spot to work—ideally, your plumbing is lined up just right so you can finish before your neck cramps up!

Double-check all your connections. Fill the bowl with water. Then let it out and watch for leaks. Tighten leaky joints. If this doesn't work, you'll have to take apart the leaky joint and make sure the rubber slip joint gaskets are in place and the brass ferrules on the compression fittings are squarely seated.

Back to Top

Shopping for pedestal sinks

Before pedestal sinks became popular again, you had to scrounge around the salvage yards to find one, but today you'll find half a dozen styles in stock at most home centers, and dozens more in manufacturers' catalogs. The sinks are 20 to 30 in. wide and cost about $70 to more than $700. First pick out a faucet. Then buy a sink with holes to match the faucet.

You'll need a few additional parts and supplies. Buy a 1-1/4 in. 17-gauge chrome-plated trap assembly to connect the drain. The metal pipe cover (escutcheon) that comes with the trap is too shallow to cover the PVC trap adapter and nut we'll be installing, so buy an extra-deep escutcheon (Photo 17). If you don't have them already, buy two shutoff valves. Buy valves with a compression fitting to tighten onto 1/2-in. copper pipe (Photo 10) or valves with pipe threads if you're connecting to the old threaded iron pipes. Buy faucet supply tubes to match your faucet. If your faucet has “pigtails” like ours that are too short, buy two 3/8-in. outside diameter extension tubes (Photo 16).

Many faucets have no tubes attached. For these, buy standard faucet supply tubes. The rigid chrome-plated ones like the ones we're using look the best, but flexible braided stainless tubes are much easier to hook up. Buy a small container of plumber's putty (Photo 13) and thread sealant for the sink tailpiece (Photo 14). All these plumbing supplies are available at home centers and full-service hardware stores. Pedestal sink mounting systems vary. Read the directions included with your sink to find out what you need.

Back to Top

Additional Information

Back to Top