Installing an undermount sink requires careful planning and
coordination between subcontractors
The demand for undermount sinks is growing. Even if you
haven't had to install one yet, it is probably only a matter of
time before a customer requests one. Because undermount sinks -
also called undercounter sinks - are generally used only with
stone or solid-surface countertops, they tend to be found in
high-end kitchens. This raises the stakes for the builder, who
is likely to face a more demanding client, and will need to
coordinate the work between several subcontractors.
Customers who like the elegant appearance of undermounts are
willing to pay an up-charge for them - not only for the
countertop, but also for the cost of the sink and the
additional installation time. Because sink manufacturers know
that undermounts are used only with high-end countertops, they
see no reason to market budget-priced undermount sinks. In
general, the price of a double-bowl stainless steel undermount
sink starts at $400, and heads north from there.
For less-expensive laminate countertops, a drop-in sink -
also called a self-rimming sink - is usually required, because
the sink cutout exposes the vulnerable particleboard substrate.
However, Counter-Seal is now marketing a system for installing
undermount sinks with laminate countertops (see sidebar, ).
A Wide Range of Materials
Like drop-in sinks, undermounts come in a wide range of
materials, including cast polymer, stainless steel, enameled
cast iron, enameled steel, vitreous china, copper, brass, and
Cast polymer Cast polymer (plastic)
sinks make up a growing share of the market. Sink manufacturers
generally divide cast polymer sinks into three different
categories - cultured marble, solid-surfacing, and composite
(see sidebar, ). Although cultured marble is relatively
inexpensive, it is less scratch resistant than other types of
cast polymer, and is not recommended for use in the kitchen. At
least one manufacturer, Lippert, makes an undermount bathroom
lavatory out of cultured marble.
Solid-surfacing. Most manufacturers of
solid-surface countertops also manufacture sinks out of the
same material. Solid-surfacing, unlike cultured marble, is
uniform throughout the entire thickness of the material. Any
scratches can be sanded out, with no degradation of the finish,
using 180- to 300-grit sandpaper.
Solid-surfacing is less stain resistant than most other sink
materials. "There are certain stains that none of the
solid-surface materials can resist," says Steve McNally,
director of government and regulatory affairs for the
International Cast Polymer Association, an industry group.
"Cherry Kool-Aid is one. It is a very aggressive stain. In
writing the national standards, we don't include resistance to
cherry Kool-Aid, because nothing would pass if we did." Stains
in solid-surface material, like scratches, can be sanded
Figure 1.When a solid-surface sink is used
with a solid-surface countertop, it is usually fused with the
countertop, making an integral unit. This oval solid-surface
lavatory (left) is manufactured by Swan. Solid-surface kitchen
sinks are also available as apron-front models, like this
single-bowl sink from Corian (right)
Solid-surface sinks for both the kitchen and the bathroom
are available from several manufacturers, including Avonite,
Corian, Fountainhead, Lippert, Swan, Transolid, and Wilsonart
(see Figure 1 above). Solid-surfacing fabricators can also make
custom sinks in almost any size.
Manufacturers usually use the
term "composite" to describe a hard, scratch resistant type of
cast polymer sink made with a filler of quartz or granite. High
quality composite sinks, like solid-surface sinks, tend to have
a high percentage of filler, resulting in a relatively high
density. Blanco, Franke, Moen, and Schock all make composite
undermount sinks (Figure 2).
Figure 2. Cast-polymer sinks with acrylic resin and
quartz filler are often called composite sinks. This kitchen
undermount is made by Blanco, which calls the material