How to install an undermount sink to your bathroom counter top.

Discussion in 'Shower & Bathtub Forum & Blog' started by johnfrwhipple, Apr 13, 2012.

  1. johnfrwhipple

    johnfrwhipple BATHROOM DESIGN & BUILD

    Jul 20, 2009
    Design Work
    North Vancouver, BC
    Installing an undermount sink is a process that is done by many different trades. Sometime the sink is factory installed and comes as one big piece. Other times the sinks are installed by the counter top installers.

    Or later by the plumber.

    Over the years I have seen all sorts of techniques and this one here is my favourite. I would like to get some feed back from you pros as to how it might be improved.

    For one I love the ease of install. This is a job I can do alone but one made easier with my helper. We installed both sinks in 30 minutes total. We used 10' of stainless steel strapping and 1/3 tube of clear silicone.

    We start by setting two straps to the side of the vanity or plywood support of the counter top.

    Then we apply clear silicone and hold the sink in position while I screw down the two straps. We are looking for light pressure here so we can have a little play above to fine tune the sinks position.

    Once set we leave the sink to set up overnight.

    The plumber will come and have the sinks set and will be able to hook it all up!

    We have found that some sinks and vanity designs make for a problem install and the faucet needs to go in first. Most projects are smooth as silk and this rig works well.

    I will back off the steel straps a hair today and get some kind of bumper between the sink and the strap.

    What other techniques do you guys use to install your sinks?
    Last edited by a moderator: Nov 26, 2016
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Feb 6, 2011
    NW Ontario, Canada
    That looks like the sink I installed in my bathroom. The sink was adhered to the granite with clear silicone before the counter was installed. I made hardwood support strips that went under the flange to provide a safety support and to support the cabinet face.
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  4. hj

    hj Master Plumber

    Aug 31, 2004
    Cave Creek, Arizona
    SInce you have wood strips to screw your "slings" to, why not just use the common "Z" support brackets, (usually supplied with the sink), screwed to those same strips? A jack, brace, or support rod though the drain opening will hold it in place while it s being anchored. Why is the opening in the countertop so much larger than the sink bowl? Usually it is cut to fit.
    Last edited: Apr 13, 2012
  5. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    The straps probably work ok on that specific sink, but would be less effective on a typical round or oval sink.

    Frankly, they do not lend a "professional look" to the job.
  6. cacher_chick

    cacher_chick Test, Don't Guess!

    Jan 5, 2008
    Test, Don't Guess!
    Land of Cheese
  7. kevinp

    kevinp In the Trades

    Apr 13, 2013
    Let me be totally transparent.. I manufacture Sinkits sink clamps, a new clamping system for mounting undermount sinks to stone and quartz counters.

    That being said I have 18 years experience as a stone fabricator installing undermount sinks.

    There is more than one way to skin a cat, but one thing for sure, depending on any type of adhesive to permanently hold a sink beneath stone without some means of a mechanical attachment is a potential problem waiting to happen. I know there are many sink installations doing just fine with adhesive being the only means of attachment out there but they are the lucky ones. The fact is there is a huge problem in our industry of sinks becoming unattached from stone and quartz countertops, the majority of these failed sinks are due to no mechanical means of attaching the sink.
    Like I implied before, there are several good ways to mount sinks using mechanical means combined with adhesives.
    Please do not depend on adhesives to be the sole means of attachment.

    By the way, my company use Sinkits on 95% of our undermounts, if there's no room for Sinkits we will build a cradle for the sink to rest on.
    Last edited: Apr 14, 2013
  8. OliverMiguel

    OliverMiguel New Member

    Apr 17, 2013
    Euless, TX
    You have done it quite well johnfrwhipple, 30 minutes is really good.
    Last edited: Jun 30, 2013
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