Forgive my lack of knowledge here.

New bathroom vanity.
Black granite countertop and 3" tall backsplash.
Countertop, and will-be-visible faces of backsplash, are polished and factory sealed.

** Backsplash will be about 2" from wall **

What specific product is best to use to "glue" the backsplash to the countertop?
(googling seems to suggest some sort of epoxy, but wondering if that might be too brittle, or discolour...?)

Do I need to sand the polished & sealed countertop where the backsplash will sit?

Do I need to caulk when the "glue" is set, and with any specific caulk?

Here's the relevant bit of the "installation guide". There is no text...

excerpt from unhelpful installation manual

Thanks in advance...

**** EDIT **** For clarification, the backsplash won't be against a wall but it will be near it. About 2 inches away. And we have little kids so I'd like to use the backsplash to stop stuff running down the back of the cabinet where it will be hard to clean.

  • As others have said, don't know why you'd want to do this. But on one granite top job I had done, they just used a good quality clear silicone caulk for the backsplash and where two pieces of the top came together.
    – SteveSh
    Apr 27, 2020 at 17:08
  • And, I think that illustration is for a typical against-the-wall installation.
    – SteveSh
    Apr 27, 2020 at 17:11
  • silicone caulk will not provide the holding power of epoxy or resin based products used to join seams or a backsplash to the top Apr 27, 2020 at 19:59
  • 1
    I was just relaying what the granite provider did.
    – SteveSh
    Apr 27, 2020 at 23:17

2 Answers 2


Clear, slow (ie, not 5 minute set time) epoxy is what I'd use. Apply masking tape on the countertop exactly at the seam line. Same for the backsplash. Glue and set the backsplash (clamp gently in place), and wipe the joint clean of the excess. (Disposable gloves will be your friend, here, as epoxy is hard to clean.) Pull the tape and wipe the joint one more time. Have whatever recommended solvent on hand for cleanup in case you get any epoxy where it shouldn't be.

My gut feeling is that this sort of setup is usually used against a wall, so they aren't expecting the backsplash to take a lot of abuse. Since you aren't against a wall, be careful in the future.

I don't think there's a need to rough up the mating surfaces, but it can't hurt.

And since you have a perfectly waterproof joint, I wouldn't bother with caulk.

  • 1
    I agree with not caulking unless it's used to hide sins. Like getting the epoxy too thick and the backsplash doesn't sit fully flush against the countertop. Of course, extra care to prevent this in the first place would be the first line of defense.
    – FreeMan
    Apr 27, 2020 at 16:08
  • What happens to the granite below this when someone loses balance and pushed on the corner of this piece?
    – DMoore
    Apr 27, 2020 at 16:12
  • @Aloysius - Thanks! Any specific epoxy recommendations from your experience?
    – ttt
    Apr 27, 2020 at 18:44
  • @DMoore - are you thinking that something more flexible might be better so the countertop itself doesn't get damaged in an accident? The unit will be close to the wall (~2") so hopefully little chance of bumps.
    – ttt
    Apr 27, 2020 at 19:13
  • @ttt - Epoxy is super rigid. We simply don't use it to install things for support. Epoxy is used to install things so they don't move. There is nothing to support this - you could install a bracket but this gets complicated and might not look good. Also I have serious concerns how well it would bind to polished granite. These trim pieces simply aren't made to install like this. You caulk them to the wall - even during a normal install there is no binding to trim to top of granite.
    – DMoore
    Apr 27, 2020 at 19:38


If it isn't against a wall then it serves no function. The point of the backsplash is so the wall isn't hit with water. You want water on the sink (in a normal vanity situation) to go to the floor.

Since in your situation water will go straight to floor, this piece is completely non-functional. Not only is it non-functional, but please ask the manufacturer if they recommend it being installed - not against a wall.


  • The back of it will be unfinished and look bad.
  • Even from the front it will not look good and be weird sitting up there like that.
  • If you glue/epoxy it you make break the granite below if it is bumped, hit or whatever
  • If you glue/epoxy it and it is bumped, it could be dangerous

Instead add molding

An alternative and there are several different types of trim based on the look you want is to install a matching granite trim piece. An example below is granite pencil molding. You could simply apply clear silicone to install this. It will look better, function better, not be a hazard and if it ever does come off it won't take the other granite with it.

enter image description here

  • 1
    I would argue that while the primary function of a backsplash is to keep water from the wall, there is an additional function, when not against a wall, of keeping stuff off the floor. Toothpaste, soap dish, etc. - a backsplash, even just a few inches tall, functions as a wall to keep stuff from falling onto the floor. If will-be-visible faces of backsplash, are polished and factory sealed is indeed correct, then both sides are polished (which may be easier for a factory produced product than dealing with returns on backwards installations) and it won't look bad. Apr 27, 2020 at 16:26
  • While it is not connected to the wall, it will prevent water from flowing down the backside of the cabinet, Apr 27, 2020 at 16:30
  • 3
    @ttt -- is there a question like, "how do I get my vanity closer to the wall?" that we might help with? Apr 27, 2020 at 18:52
  • 1
    I would basically fill in the gap with wood screwed/nailed to the wall. Mount the wood so the top is flush with the top of the backsplash. Paint to match the wall. Essentially a 2" ledge between the wall and the backsplash. Backsplash is flush against it (and therefore safe & secure). Apr 27, 2020 at 20:48
  • 1
    Yes, silicone sounds good. Apr 28, 2020 at 0:36

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