undermount kitchen sink

Discussion in 'Remodel Forum & Blog' started by pitterpat, Nov 22, 2005.

  1. pitterpat

    pitterpat HandyWOMAN

    Messages:
    46
    Location:
    Indianapolis
    You guy's and gals have any good tips on installing an undermount kitchen sink? This will be on granite, quartz or Corian like solid surface? Also how about pricing....$900 - 1000 US. Any books, links or articles as to the best way to do this?
    Tks
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Work closely with your granite installer. And forget about attaching any mount clips to the granite; not a good idea.

    Amer. Std, and Kohler, as well as some generics, make undermount bracket kits. These take the form of bars supported by the cabinet sides, or front-back. They and the sink are installed before the granite. Then after the countertop is on, adjuster screws snug the sink up to the countertop ( with a bead of caulk of course.) Very easy to do, sink is extremely secure, and the sink can be removed if necessary in the future without disturbing the top.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    On the three undermount sinks I have in my place (I used the same granite fabricator for all of them), they use a router bit to make T-slots. You slide the T-bolts into them, and using clips, snug the sink up after putting on the silicon. Works fine. Now, if it was a heavy cast iron sink, they might do it differently (two porcelain bathroom sinks and one SS kitchen sink), I don't know, cause I don't have one! The fabricator I used charges $300 for a simple kitchen sink including polishing the edges, T-slots, and faucet holes, and $250 for a vanity.
  4. finnegan

    finnegan New Member

    Messages:
    250
    Location:
    CT
    If you are installing the sink prior to the counter, you can build a frame within the cabinet, lvel the top of the sink to the top of the cabinets and set the sink in silcone just to keep it in place. The counter top guys will take it from there.
  5. spitz

    spitz New Member

    Messages:
    2
    How would I go about replacing an existing undermount sink? The counters are granite and the sink has already been installed. Would I just disconnect the plumbing, unscrew the bracket mounts, pry away the sink (caulked on) and reattach the new sink in the same drilled holes from the old sink?
  6. undermount sink

    you are far far better off to let the granite guy

    provide and install the undermount sink........


    most granite guys around here will do it fro free
    cause they need the sink to
    make a templatte anyway to cut it out.....


    jsut let them do it ---no matter what the cost.....

    you will save yourself tons of grief and misery trying to do his job
  7. Kristi

    Kristi Tradesman Plumber

    Messages:
    176
    Location:
    Vancouver, BC
    well I've installed a few, and haven't found them to be that big of a deal. I don't like giving all my good secrets away, but here goes another :)

    - the countertop can be set ontop of a plywood "undertop" (new term made up on the spot)

    - silicone the rim of the sink

    - measure and set an abs leg that will jam the sink up against the granite while the silicone sets - clean up that gooey inside edge and make sure she's centred beautifully!

    - run steel strapping (4 long strips) - 2 from left to right, 2 from back to front (a strap on either side of the drain, of course, in each direction); screw the strapping tight to the plywood

    - remove the abs leg the next day and hook up the drainage. you're good to go!
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    My granite fabricator uses a router (probably on a cnc machine) to cut angled T-slots in the underside of the slab. Slobber silicon on the flange of the sink, hold it up, center it, slide in the T-bolts with clamp, tighten and you are done. I wouldn't try this on 2cm slab, but on 3cm stuff he has the bottom of the slot maybe going through 2/3rds of the slab, so it is quite strong.
  9. Sherm2005g

    Sherm2005g New Member

    Messages:
    2
    Location:
    nyc
    I am going from a formica overmount sink to a granite undermount sink. Current overmount sink is 8" deep and the new undermount is 9" deep. Accounting for the lowered placement of the new sink, will that affect the ease of re-attaching the drain pipe? And if so, how do I adjust for it?
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    Maybe, maybe not. Depends on the height of the arm that goes into the wall. If the sink is too low (i.e., lower than the arm), you'll have to tear the wall apart to rebuild that connection to get it lower. Water doesn't flow uphill.
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,045
    Location:
    Cave Creek, Arizona
    The largest part of the price is the cost of the sink, and for that you have almost unlimited possibilities. I mount the sink into the cabinets with the rim level with the bottom of the granite. The mount can either be metal saddles with adjustment bolts to raise and hold the sink, or a wooden framework attached to the cabinets. Set the sink onto the supports, apply the necessary sealant, and then put the granite top over it. The sink can be hooked up as soon as the granite guys leave.
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    My granite fabricator uses his CNC machine to mill T-slots in the bottom of the slab to hold T-bolts and clips which hold the sink (mostly while the silicon cures). this works fine for SS, but you'd probably want something else for a CI sink. Some fabricators drill holes and epoxy in studs, some don't do anything other than make the hole and leave it up to the plumber.
  13. rockymeet

    rockymeet New Member

    Messages:
    1
    Location:
    Maryland
    Step 1: Have a Professional Cut a Hole

    Before beginning, have a professional fabricator cut the sink hole using a template. Sink bowls come in varying sizes and arrangements so you can select the configuration that best meets your needs. Think about your fixtures too. Do you want a double-handle or single-handle faucet? What about a soap dispenser? Since the weight of the sink is supported from the underside, you'll need a solid surface countertop such as granite or marble.



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    Step 1: Have a Professional Cut a Hole

    Before beginning, have a professional fabricator cut the sink hole using a template. Sink bowls come in varying sizes and arrangements so you can select the configuration that best meets your needs. Think about your fixtures too. Do you want a double-handle or single-handle faucet? What about a soap dispenser? Since the weight of the sink is supported from the underside, you'll need a solid surface countertop such as granite or marble.
    Step 2: Test Fit the Sink

    Place a 2x4 across the countertop, clamp the sink to the underside and adjust the placement. Thread the wing nuts onto the screw heads. Test fit your sink and mark the location for the mounting clips. With the sink out, drill 1/4" holes for the brass inserts and tap them in. Clean the ridge with denatured alcohol. Run a bead of silicone sealant around the edge, and re-clamp the sink in place..

    Step 3: Secure the Sink Bowl

    Thread the wing nuts onto the screw heads and tighten the screws to anchor the inserts. Hand tighten the wing nuts to secure the bowl. After removing the clamps, place masking tape across the back of the countertop and mark the layout for the faucet holes. Drill the holes using a 1-1/4" diamond coring bit. Allow it to cure overnight before installing your plumbing.
  14. Repeating what Jimbo posted, and adding a few caveats.

    Work together with your stone countertop guys -- but don't assume they know best. Some of them will not leave the stone as is, and will cut it, rod it, etc. There is no need for them to do this. It increases risk. Braxton Bragg is one of the "generic" names that Jimbo referred to : Sink Setter
    http://www.braxton-bragg.com/index.cfm/m/1/fuseaction/store7catalog.level/bc/0,8457,8580,7105/
    http://www.braxton-bragg.com/index.cfm/m/1/fuseaction/store7catalog.level/bc/0,8457,8580,7106/
    http://www.braxton-bragg.com/index.cfm/m/1/fuseaction/store7Catalog.level/bc/0,8457,8580/
  15. mtoMA2AZ

    mtoMA2AZ New Member

    Messages:
    5
    Location:
    Phoenix AZ
    Is it possible to REPLACE an existing undermount sink? I currently have a black enamel Kohler double sink, which no amount of cleaning gets looking good - it was like that when I bought the house. I hate it, and would like to replace it with preferably a black matte finish composite Mont Blanc or similar sink. However, I just went to Lowe's and was told it is impossible to replace a sink without installing completely new granite countertop. That there is no standardization of sink size (and therefore of the hole already cut in the current granite) etc. Is this true? That sounds ridiculous to me! It DOES look like from what you're saying above, that I WILL have to hire a granite guy to install the sink. Am I doomed to have this nasty black sink forever? Or must I go to the expense of replacing all my granite counters just to get a new sink? I wouldn't have installed granite myself; I just don't get what's so great about it. But I digress...
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    There is no such thing as a standard sized sink, so finding a new one that would work and look good in the existing hole is a crapshoot...you might find one, you might not. They're called custom granite counters for a reason...they are made for both the room and the sink and valve.

    The existing sink is probably installed with both some clips and epoxy and maybe a frame underneath.

    Carefully measure the opening, and then start looking around for a sink that is close. Your better bet is to call a granite fabricator rather than an intermediary that is giving you the company line. It is possible to cut a sink hole on site, but it is messy and risky. Much better done in the shop. The existing hole may need to be revised to enable any new sink to fit. The alternative is to switch to a drop-in sink big enough to cover the existing hole(s), or live with what's there.
  17. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,045
    Location:
    Cave Creek, Arizona
    quote; That there is no standardization of sink size (and therefore of the hole already cut in the current granite

    The overall size of the sink is "stardard", but the sizes of the individual bowls, the location of the faucet, etc. could be different than your existing cutout can accomodate.
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    All the better undermount sinks come with a CAD file for the fabricator to make the 'perfect' hole for that particular sink. If they use that to cut the hole, there will be a nice, even, consistent lineup of the sink and the hole. Done wrong, there will either be a big stone overlap of the sink or the mounting flange will partially show. Now, can you get one to fit? Probably. Will it look as good as it was designed to? Probably not. Will you care if the existing sink drives you to change it? Maybe. Sinks come in various shapes - rectangular, square, D-shaped, small bowl and big bowl in a combo, big, small, big combo, and probably others. Given the depth of a standard counter, there are limits on how big a sink can be, but someones rough size doesn't dictate the actual bowl size, only the flange size. It's a crap shoot as to what you can find that will fit AND look good.
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