Here are factors to consider when specifying lavatories and vessels.

A vessel lavatory sits above the counter, so add both the height of the counter and the height of the lavatory together to get the total finished height. (Photo courtesy of Lori Carroll – Tucson, AZ.)

With this issue Supply House Times is kicking off a new year-long kitchen and bath educational series in partnership with the National Kitchen & Bath Association. Articles will be excerpted from various books in the NKBA’sProfessional Resource Library,a series of comprehensive educational books for the plumbing industry. They will focus on recommendations for specifying today’s more complex kitchen and bath products to ensure successful projects for everyone involved - from the showroom to the designer to the end user. This first article, excerpted fromKitchen & Bath Products,focuses on lavatory planning tips for pedestal lavs, self-rimming lavs and vessels.

When specifying pedestal lavatories, considerations include the base, the pipes, the wall finish behind the base and the choice of faucet. Following are factors to consider.

The pedestal base may be open all the way down the back, may be solid up to 16 inches off a finished floor or may have a horizontal support bar connecting both sides of the pedestal base somewhere along the back. These last two fixture designs may interfere with the drain location. Therefore, read the manufacturer’s specifications to verify what the back of the pedestal base looks like and where the drain line should be roughed in.

Because the pedestal base is at least partially open, do not install a mirror behind the unit. To maintain continuity, remember to consider the decorative finish on the shut-off valves, P-trap, box flange and supply lines as you select the other fittings in the bathroom.

If the pedestal lavatory does not completely support its own weight, the installation may require reinforcement behind the finished wall surface.

Because the plumbing lines are exposed behind the vertical pedestal base, it is critical that the drain and supply lines are dimensionally balanced behind the pedestal. This is far less critical inside a vanity cabinet, where the supply lines can be anywhere within the open cabinet space. For a pedestal lavatory, the rough-in dimensions must be perfectly centered on the pedestal - make sure the plans are accurate.

Selecting The Right Faucet

Your choices of faucet handle style and escutcheon plate diameter may be limited if the pedestal lavatory has a small back deck or if there is an integral splash along the back of the fixture. If you are specifying a fitting that has not been designed to fit on the pedestal lavatory by the fixture manufacturer, verify that these two items are compatible by reviewing the dimensional information from both companies.

The design of some pedestal lavatory bases limits the shut-off valves to about 16 inches off the finished floor. This height dimension is as important as the vertical arrangement mentioned above.

Self-rimming Lavatory

The weight of the fixture, the sealant, the supply lines and the trap hold the lavatory in place.

Self-rimming lavatories are susceptible to warpage. Large lavatories, and particularly oval designs, may not fit flush on the countertop. Because they do not rest perfectly on the countertop surface, they will require a larger caulking line. The client must understand this and must be willing to accept the fixture with this installation.

For some hand-made china self-rimming bowls, no template will be available. In a bathroom with more than one lavatory, do not allow the installer to use one bowl to template all the lavatories - there may be a slight difference. Therefore, each lavatory should be used for its own template in this unusual decorative situation. As a general rule, make sure the self-rimming lavatory is on the job when the countertop is cut. That way there will be no mistakes!

Ledge Drilling

The drilling location for a self-rimming lavatory must be verified before the cabinetry is ordered. Most standard self-rimming lavatories have one hole: a 4-inch center set drilling or 8-inch to 12-inch widespread drilling as part of their back ledge. Therefore, no special dimensioning is required because the overall depth of the lavatory will accommodate the bowl, the overflow and the plumbing lines to the faucet. However, pay particular attention to the number and diameter of the holes drilled in the lavatory. A mini-widespread faucet does not use an escutcheon plate and has rigid piping, so there is no flexibility in the distance separating the valves from the spout. Therefore, if there is any discrepancy between the drilling holes on the lavatory and the faucet drilling it will not work.

Another compatibility problem may occur when you attempt to specify a single-hole faucet with an escutcheon plate on a lavatory faucet that has been drilled with three holes. Sounds simple enough - you are going to use the escutcheon plate to cover the two unused holes. The problem is the diameter of the hole. On many lavatories drilled for a standard 4-inch center set, the center hole will only be 1-1/8 inches in diameter. For a single-hole faucet, you need 1-1/4 inches. It is difficult and expensive to drill a cast iron lavatory. The potential for damage is great, as well.

When specifying pedestal lavatories, considerations include the base, the pipes, the wall finish behind the base and the choice of faucet. (Photo courtesy of Porcher.)

Vessel/Above-counter Bowls

Installing a sink that sits on the bathroom counter or is partially recessed in the counter has special planning concerns. These concerns revolve around the height of the user, the faucet location and the relationship of the vessel bowl to the countertop.

Placing a vessel bowl atop a typical 32-inch to 36-inch high vanity cabinet may be too high for a more petite user and definitely inappropriate in a children’s bathroom. Consider the actual physical height of the individual who will be using the vessel sink: if need be, partially recessing the vessel fixture may give you the “look” without the added height.

Faucet Location

Plumbers are not accustomed to vessel bowls - the craftspeople on the project need to be aware that the faucet positioning will be very different for this type of special lavatory. A wall-mounted faucet needs to be exactly positioned by the designer for the craftsperson on the job. If a wall-mounted faucet is not being used, special decorative deck-mounted faucets that are installed adjacent to the vessel sink (not behind because you cannot reach the overflow or the controls) need to be specified.

The designer needs to think through the material of the countertop, the material of the vessel bowl and the waterproof caulking compound that will be used to join the two together. In many installations today we see beautiful glass vessel bowls in glass countertops - the finish and fit of all plumbing (which is now dramatically exposed) must be thought through before the project is finalized - from a planning and budgeting standpoint.

This article is excerpted from Kitchen & Bath Products, one of the first nine books in the NKBA’s Professional Resource Library. Written by recognized industry experts and thoroughly reviewed by top technical editors and peers, the volumes cover design, products, residential construction, mechanical systems, business practices, drawing, project management and more. They are available only through the association, at or call 800-THE-NKBA.