Trying to understand undermount sink requirements

Discussion in 'Remodel Forum & Blog' started by prwood, Oct 12, 2019.

  1. prwood

    prwood New Member

    Jan 26, 2019
    Salem, MA
    We are remodeling our kitchen, and are trying to decide on the kitchen sink and counter tops. We are interested in an undermount sink for the clean look and the ability to clean up straight from the counter into the sink without a sink lip in the way.

    As we try to balance looks and budget, one thing I'm having a hard time understanding is what materials you can actually use with undermount sinks. The most consistent recommendation I see is to use stone, stainless steel, or solid surface countertops with undermount sinks, for the following reasons:
    - they aren't as susceptible to damage from water seepage that occurs with an undermount sink
    - they are strong enough to support the fasteners and adhesive needed to hang the sink from underneath

    However, I've also read in a number of places about DIY methods for installing undermount sinks in laminate and plywood countertops, and they usually involve something like the following:
    - Using proper sealants and adhesives to protect the wood against water damage.
    - Flush-installation methods where you cut out a groove from a wood counter for the sink to sit in, then install laminate panel over top and cut it away. So, not exactly undermount, but does achieve a countertop with no lip around the sink.

    So is the issue just that a structurally sound and water resistant undermount sink is more work in wood-based counters than in other materials? Or that it's possible but not recommended? Or can it really not be done?
  2. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    1. Will you have a garbage disposal?
    2. What height is your trap adapter at the wall, with respect to the bottom of your new sink?
    Know those things before picking out a sink. It may seem obvious, but you would be surprised.
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  4. WorthFlorida

    WorthFlorida Retired

    Oct 28, 2009
    Orlando, Florida
    Undermount sinks are for solid surfaces countertops as you mentioned. Any kind of material that can absorb water will, so don't waste your money trying to make it work with wood or laminate. Might look OK at first but after a few years the water proofing will degrade and then look bad. The kitchen sink is about the most abused appliance in a household.

    I'm in my second home with granite counters and with undermount sinks with a disposal. Underneath the granite is grooved to accept clips that hold the sink. Usually two on each side and two in the back. The front part may slip between the granite and cabinet that will provide support. The adhesive is used also helps support the sink and it waterproofs the joint.

    My current home, about two years ago the SS sink broke lose while it was full of water. The front lip between the granite and cabinet saved that day. The problem was 1) I was not present when it was installed. 2) the cheap bastard's did not use the correct adhesive. It was non flexible construction adhesive, not 100% silicone. 3) Only two out of six clips were used. I did not hire the installer, the kitchen design company did. The fix was I used silicone and purchased hardwares from ACE Hardware and I fashioned the four clips needed. It was the weekend and too far away from suppliers to find them. Too long a wait buying them online.

    I now have four porcelain bathroom sinks hanging from quartz countertops. No issues at all. You may find that kitchen laminate countertops are nearly as expensive to fabricate as granite or quartz. The popularity of quartz has caused the price to drop some but there are some very expensive ones also. When I did the main bathroom last year, I contracted everyone and purchased everything I needed. A counter top company in Orlando, Fl buys their own OEM quartz countertops that emulated marble. Buying a name brand really cranks the price up. The best part was this company only charged you by the square foot, etc. Other fabricators charges you for the entire slab since they have to buy the entire slab thought you may only need a fraction of it. If you shop around you might be able to come across leftover pieces of slabs that may fit your need and the price drops dramatically.
    FYI... the granite, marble and quartz suppliers sell only to fabricators. Some fabricators will buy a few slabs of material for stock to show to customers. Suppliers do not sell directly to the public.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    It depends on where you live and the supplier you choose...the place I got several counters made has their own fab and install shop out back of their showroom. I was able to walk through their storeroom and pick out the slabs that I wanted. Some stone is quite consistent, some can vary radically from one slab to the next, and, if you need more than one, your best bet is to find a place that has successive cuts from the same block. Using manufactured stuff is's pretty consistent from piece to piece.

    There are ways to use an undermount sink with a tiled countertop. One way is shown here
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