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nonnyx2

Mold/Mildew issues with undercounter sink?

nonnyx2
14 år siden

We are remodeling/relocating our kitchen and wanted an under counter sink but my sister said she has heard, from more than a few, about issues with mold and mildew. She lives in Virginia we live in Michigan.

The folks she spoke with have beautiful grand homes with expensive summer homes at Hilton Head.

All were professionally installed but not by the same installer.

Is location the problem? The installation?

Thanks in advance for your input.

Fremhævet svar
  • Buehl
    14 år siden

    Well, this is the first I've ever heard that anyone has had mold or mildew with an undermounted sink (I assume that's what you mean). I live in MD, so I'm in the same region.

    I wonder if what she's really talking about is the "gunk" that can collect under the countertop rim when you have a negative reveal (i.e., the countertop extends past the sink sides). This is not a problem w/positive or zero/neutral/flush reveal. However, as long as you're fairly good about wiping down the underside of the countertop when wiping down your sink, I don't see how this would be a problem.


    Sink Undermount Options

    There are pros & cons for each type of reveal:

    • Positive Reveal. The sink shows; granite cutout is slightly larger than sink (some people say it "frames the sink")
      • Pros: Easier to clean b/c you can see the gunk and can easily wipe it off (it only gets nasty if you leave it there)
    • Cons: Silicone (caulk?) is visible, but if they use clear you won't see it when it dries

    Negative Reveal. The granite overhangs the sink; granite cutout is slightly smaller than the sink

    • Pros: You cannot see the gunk buildup or silicone/caulk

    Cons:

    • You cannot see the gunk to clean it. (Since it's a working sink, gunk will get underneath the overhang and you won't know it unless you look)

    • Dirty water/food can splash up & under where you cannot see to clean it. It's difficult to see underneath w/o leaning pretty far over & into the sink.

    • Dishes/glasses have been known to break b/c when you lift them out near the edge of the sink the dish hits the stone counter & can break

    • For softer stones, pots & pans can chip or ding the edge of the stone around the sink if they bang against those edges

    • The granite often isn't polished under the reveal so things are more likely to "stick" (I don't know if this applies to Soapstone)

    • Won't know if caulk needs to be repaired (possibly allowing water to get into & damaging the sink base)

    Zero Reveal or Flush. Sink & granite are flush or even; the granite cutout & sink are the same size

    • Pros:

      • Easier to clean b/c you can see the gunk

      • No platform over or under for the gunk to collect

    Cons:

    • More difficult to do perfectly

    • Silicone is visible, but if they use clear you won't see it when it dries

    Many granite installers prefer a negative reveal b/c they don't have to be as careful during install to match the template exactly as you do w/a positive or, especially, a flush reveal. [Note: This is definitely not true of all installers. Many are very conscientious and do a very good job.]

    And that may be the problem...poorly done & installed negative reveal + not realizing how to clean.

    So, do your homework and get a good installer!


    BTW...just b/c you have an expensive house doesn't mean you have quality products or installation...I know as we live in an area w/very expensive homes (DC-metro area) and I've seen cheap cabinets, poor installation, & very...

    (17) kommentarer

    • annie.zz
      14 år siden

      geesh, I have to worry about that???!!!

      I think that vacation homes in hilton head are probably very humid, leading to more mildew issues.

    • nonnyx2
      Forfatter
      14 år siden

      Thank you, beuhl! Your clear information has solidified my decision to purchase an undermount sink.
      Maintenance is what may very well be the cause for the problems she mentioned.

    • morton5
      14 år siden

      There is such a thing a mildew-resistant caulk, make sure they use that.

    • nonnyx2
      Forfatter
      14 år siden

      morton, Thank you! I will surely do that! You are all just fantastic!

    • earthpal
      14 år siden

      Wow! Another one of those little details that I would have had no clue on how to answer when my countertops arrive! Thank you Buehl and Morton 5!!!

    • holligator
      14 år siden

      I think your sister is confused. I live in what has to be the mold and mildew capital of the world and my sink is one place it hasn't thought to grow. I can't imagine what kind of a slob someone would have to be for their sink to get gross enough for mold or mildew to grow there.

      Get your undermount sink and don't worry about this particular issue for another second.

    • lesmis
      14 år siden

      Maybe the issue is that these are vacation homes in Hilton Head so there is a sufficient amount of time between people using the sink and maybe renters aren't as neat? I too had heard that it could be an issue, yet when I talked to friends who had undermount sinks I couldn't find anyone who had actually had problems with mold. We ended up with a farm sink but I wouldn't hesitate to get an undermount sink! The corners of my farm sink would get yucky if I didn't wipe them out from time to time as well, so I think people are spot on when they say you'd have to ignore wiping down your sink for quite awhile before you'd have any major issues.

      Kat :)

    • regan123
      8 år siden

      I realize these comments were from several years ago but I too have this issue and, I am not a slob and I live in Massachusetts where heat and humidity are limited to a couple months a year. However, I will begin to use a toothbrush to clean this area regularly. Although the mold has become visible it is very hard to reach. I never have known anyone to need a toothbrush to clean where the sink and counter-top meet but I am going to begin using a toothbrush regularly to reach this area. I would think twice before getting another under-mount sink. The black mold that builds up is disgusting and almost impossible to reach. I am going to replace the molding today with the mold resistant caulking someone mentioned in this thread and see what happens.

    • Ruth Marco
      7 år siden

      I have been considering the possible issue of mold on an undermount sink, which is how I got to this informative site. I wonder if I can have my stone fabricator polish the underside, for a couple of inches around the sink, before installing it. Would this make it less susceptible to molding?

    • PRO
      Joseph Corlett, LLC
      7 år siden

      " I wonder if I can have my stone fabricator polish the underside, for a couple of inches around the sink, before installing it. Would this make it less susceptible to molding?"


      Yes, and that's not a bad idea. No one has probably ever asked your fabricator to do this, so let him know you're willing to pay. I think up to $200.00 is reasonable. He should profile and polish.


      Or just get a positive reveal, have no crud ledge, and pay no extra.

    • Mary Ellen Jardine-Claypool
      7 år siden

      Are you kidding me, every undermount sink gets mold. I'm going back to the solid sink counter top. After 4 houses I'm done with undermounts.

    • PRO
      Joseph Corlett, LLC
      7 år siden

      A properly installed and maintained undermount sink does not get mold. Impossible.

    • lion rose
      7 år siden
      Sidst ændret: {last_modified_time}7 år siden

      Every undermount I have ever seen has mildewed, dirty caulking, i.e. it's no longer clear but black. Once it's turned black, it needs to be replaced. I don't know if it's improper maintenance or simply the wrong type of silicone caulking, but it can't be bleached or cleaned. Last year I bought an 11-year old house with a solid surface counter, & undermount stainless steel sink. I simply cannot get the caulk clean. We are planning a remodel and though I prefer the look of the undermount sinks, especially when used with granite, I am so disgusted by my experience I am having trouble finding a sink and may resort to a drop-in.

    • PRO
      Joseph Corlett, LLC
      7 år siden
      Sidst ændret: {last_modified_time}7 år siden

      I will pay a $10,000.00 bounty on every undermount sink I've ever installed with a positive reveal that has any mold or mildew. Flush mount Karran's included. Not happening. Ever.

    • jostra99
      6 år siden

      Please let us know your secret for preventing mold in an undermount sink with positive reveal.

      If the sink is a double bowl, there is sink surface area revealed on the front and back and that is where the mold grows, even with constant cleaning and good quality silicone caulk (which resides slightly under the granite edge). I was concerned about this prior to purchase of ours because in my 38 years of caulking experience I have yet to find ANY caulk impervious to mold. Now that I have had an undermount with pos reveal for a couple of years, I am experiencing the mold issue.

      We have always dried the neg reveal area between the bowls after every use to prevent the issue, but it has not worked.

    • PRO
      Joseph Corlett, LLC
      6 år siden

      jostra99:


      Your sink needs to be remounted. I promise if it's done right you'll never have any mold issues. Your topical application of caulk is like a band-aid on a blown tire; the mold is not the caulk's fault. 100% silicone caulk needs to be applied between the sink flange and the stone bottom. The only way that can happen is by removing and reinstalling the sink. Here's how with pictures.

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