Tips for Pedestal Sink Installation

Some helpful tips when it comes time for the installation pedestal sinks, from roughing-in to bracing and more.

The word “pedestal” is a bad word in the plumbing community; one that can make a plumber cringe. Homeowners, however, seem to love the look of pedestal sinks in the modern bathroom.

Websites and interior designers are picking pedestal sinks because of their vintage clean look; and some homeowners are buying refurbished antique pedestal sinks for big money.

What does this mean to the modern plumber? It means that you need to pay extra attention to the rough in dimensions of the waterlines and the DWV piping. More importantly it means you must pay attention to how you hang the pedestal sink from the wall.

ROUGHING-IN THE PLUMBING

If you are fortunate enough to have a situation where the bathroom remodel has open walls, you should pay close attention to the rough-in dimensions of the pedestal sink you are installing. Most pedestal sinks have a higher waste outlet than its vanity counterpart. You don’t want to break your local plumbing code by adding a tubular extension to make up the difference if the waste outlet is too low because the trap will siphon. You also don’t want to install shallow traps to make up for the elevated height.

The piping on the DWV just must be right for a pedestal to work properly. Make sure you get an inspection on the in-wall piping to make sure it’s in properly. Also make sure that your trap adapter (desanco) has its threads just barely visible from the finished drywall dimension so that a trap escutcheon will completely cover the trap adapter nut for a perfect finish.

As for the waterlines, I strongly suggest installing 1/2-inch FIP lug ear elbows firmly screwed into wood bracing inside the wall to the exact rough-in dimensions and stubbing out with the plastic plug extensions they make for extending out past the drywall. Once the drywall is completed you remove these extensions and screw in 1/2-inch chrome brass nipples. I’ve found this to be the most solid way of installation as opposed to running PEX out of the wall. PEX can be difficult to keep straight and can be difficult to adapt to when trying to make it “look nice.”

The waterlines should be stubbed out exact just like the waste outlet. Especially if you are installing stiff chrome supply tubes instead of flexible supply line. As a plumber you should push for installing supply tubes since they look much nicer, provide a more solid connection, tighten up the entire installation, and ultimately it’s one of the main differences between a homeowner and professional installation.

BRACING

Providing a means of bracing behind the wall is just as important as the rough in plumbing. Pedestals are very heavy so the more bracing you can get into the wall before the drywall or tile goes up-the better. 2x4s, 2x6s or thick plywood work well.

Make sure you take up as much room as possible with your bracing. The last thing you want is to put up a bunch of bracing only to realize after the drywall is already finished that your lag screws missed your bracing by a half an inch. It’s one of the worst feelings in the world. If you are relying on toggle bolts at this point in the project, you probably did something wrong.

If you’re installing an antique pedestal sink, you are in luck. Antique pedestals were built to be installed properly. They have clear and concise methods of providing a solid installation that include slide arm brackets that screw into the wall which also have wing nuts that slide into slot made into the bottom of the pedestal’s china as well as a long bolt that tightens the sink to the pedestal base. This requires more precise work that requires more attention and more time but is easier and more solid.

New pedestal sinks are horrible as far as this type of bracing goes. Most pedestals have a metal wall bracket that you can center with your drainlines that have tabs where the pedestal can slide down onto. These are the new industry norm. If you are slightly high or slightly low on your wall bracket the sink will either be too low and only resting on the base instead of the both the base and the bracket, or it will be too high and be relying only on the bracket which will allow the sink to be able to be pushed down and spring back up slightly. Both are wrong and should be redone.

OPEN WORK

Open work is a plumbing term referring to everything you can see in the open that needs to look nice and shiny.

You want to install the pop-up assembly and lavatory faucet on an open table before you set the sink in its final resting place to give you room to work. Once you set the sink in place you won’t have room to work. Once you have it ready, set it into its final resting place and now tighten the waterlines and the p-trap to the desanco. Don’t forget to install the escutcheons for the hot, cold and desanco. Before installing the emergency shutoff valves and the trap.

As a last note, don’t be the guy using PVC P-traps, crooked wall stub outs, exposed desancos or flexible supply lines. The beauty of a pedestal sink comes from the dichotomy of simplicity through complexity (making the complicated look simple).

Only hard pipe and plumb chrome will do on a job like this. If you are, however, installing a pedestal in place of a vanity without having the ability to get into the walls and re-rough the plumbing, do whatever you have to do to get it installed looking as nice as possible.  

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Anthony Pacilla has been in the trades since he was 9 years old (family business). He started cleaning toilets, mopping floors and putting fittings away in the warehouse. As he picked up skills, he would add becoming a ground man and laborer. When he was ready, Pacilla became an apprentice and then a journeyman plumber. He graduated college with a business and economics degree and immediately wanted to come back to work in the family business. A few years ago, Pacilla become a licensed master plumber. To contact Pacilla, email editor@plumbermag.com



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