I want to replace my undermount sink that is mounted under a granite countertop. How difficult is it to remove the existing sink? I believe it is held in place by a very strong epoxy. How would the sink be removed and would it require taking up the granite countertop?

Hi Stan...

More than likely, the sink is held in place by a silicone sealant and 4 hangers underneath the counter... see image below.

Look up under the counter and see if you see the hangers and see if the sealant holding the sink in is still 'flexible". If so, you would remove the hangers and use a sharp chisel to work the seam at the sink and loosen the sink from the silicone.

To install a new sink you would want to replace with a similar sized sink so you could hopefully use the old hangers.

If you do have an epoxy in place, then you may not be able to remove the sink without consulting a granite top installer... maybe?

Let us know what you find, OK?

Mark

Hello Mark,

Thanks for the reply. I can see the hangers holding the sink but what I am not sure about is whether there is epoxy. If there is, can the sink still be removed without affecting the granite countertop?

I had the sink/countertop installed about 2 months ago and there is a chemical type odor coming from the cabinet that I think is coming from the sink (not from the drain, from the sink body in the cabinet). There are no leaks - absolutely dry. At first I thought it was epoxy curing but it hasn't disipated in 7 weeks. It could be the material used for the sink sound dampening - I've done some searching and have found posts that refer to that. If it turns out that this is the issue then the sink will need to be replaced. I didn't part on friendly terms with the granite installer (he did a pretty poor job) so I doubt that I will be able to get him back to take care of the sink. I'm trying to get an idea of how big my problem is if the sink has to be replaced.

If it's epoxy then it was done wrong. If it's epoxy, most likely the sink can't be replaced as the chances that the granite top could crack is just too great a risk for any company to take on. Epoxy also wouldn't have a smell as epoxy cures completely... very quickly!

Is there a PTRAP present under the sink? There should be as this keeps sewer gasses from coming into the home.

Next guess, by chance, is there a mechanical vent (or similar device) under your sink... see image? If there is then this is more likely your issue as the spring mechanism could have failed and is allowing sewer gasses into the cabinet. If this is the case, the mechanical vent is easily replaced... just spins out and you replace with a new one (add thread sealant to threads).

Finally, if they replaced piping under the sink then it is possible that odors could linger from the chemicals used if the cabinet has been left closed for all 7 weeks. To test this leave the cabinet open for a few days and then close all up and see what happens after that...smell should dissipate.

Back to you...

Mark,

Yes, I believe that there is an AAV in the cabinet but given that it is a chemical type odor and the AAV is only 7 weeks old I didn't think that would be the problem. I know the springs in the AAV can fail with time and cause odors but I would think that would be more of a sewer type odor - which is not at all what I have. In addition, if the AAV fails, would the odor be in the cabinet or would it come out of the drain? One other point, the AAV is in the back of the cabinet on the left side and the odor seems to be coming predominently from the right side - although admittedly it is hard to pin point.

Is it possilble that either epoxy or the silicone that they use could still be curing this long after the installation? Doesn't seem realistic to me.

By the way, I thought that epoxy was commonly used on the hangers when installing undermount sinks. Not correct?

Thanks again.

Good point on the anchors... very common use of epoxy there, but should have cured by now. Test this by probing the anchor setting material with a knife... if rock hard then the chemical reactions have taken place and should not be an odor issue. They shouldn't ever use epoxy to install the sink.

Odor would be inside the cabinet if AAV failed, but I agree that it is unlikely issue as you seem certain the smell is chemical. Of course, if you guys use a lot of hair/chemical products then this could still be the issue, too!

Did they install new piping... possible chemical smells lingering there as mentioned earlier?

Your turn...

Mark,

Yes, the piping is all new - PVC.

I'm betting on something to do with the sound dampening material on the sink. Either it wasn't put on right and something below it is coming through or it accidentally absorbed something before the sink was installed. I have the sink supplier coming to the house on Monday morning to see what I'm talking about. I hope there's something I can do to get rid of the smell because taking the sink out and potentially damaging a brand new granite countertop is not high on my list. The sink came from China - which with 20/20 hindsight was a mistake in itself given all the bad publicity about stuff from there. I guess I figured what could you do to a sink? I guess I may have found out. I guess if it is the sound dampening material I could potentially replace it or somehow seal it with an aluminized paint or something like that.

Thanks for all the responses and the ideas.

Regards,
Stan

Hi Stan,
We just had an undermount sink installed under granite countertops and have the same problem (very smelly rubber/dampening pads). Would you mind sharing what you have tried/are trying and whether it works?
Thanks,
Dan

Hi Dan,

I haven't tried anything yet. I have done some research of the problem on line and have found several posts referring to the same problem. I am convinced it is the sink as any epoxy/silicone curing odor would be long gone after 7 weeks. I just checked and the odor is as strong as ever.

One post I found had the problem with an Artisan sink. The company told them to scrape off the sound dampening material and sent them new material to put on. That's the only one that I found with a solution. My sink was made in China and I've found a post talking about the same problem with their Chinese sink.

I have the GC and the sink supplier coming to the house tomorrow. The sink supplier was supposed to check with the manufacturer in China to see if there have been any other issues like to this and to see if there was anything they recommend.

From talking to plumbers and other knowledgeable people, removing an undermount sink is not fun if epoxy was used - and it is supposed to be used to hold the sink in place. It is extremely difficult and you run the risk of cracking/damaging the granite.

I'll post any information I get as I go forward. You do the same.

Good luck.

Regards,
Stan

From my experience, we usually have good luck with removing under-mounted sink by inserting screw driver between the sink and front edge - and carefully applying pressure to it. You may even use hammer and gently tap the screwdriver few times. Don't try to break the seal the very first time. Do it gradually and every 6 inches or so all the way around. The joint will get weaker and weaker and eventually it will break off and release the sink.

Granite people usually use epoxy designed for gluing two pieces of stone together to attach the sink to granite. When this epoxy dries it has properties of glass. Meaning, it will break off relatively easy.

Hello Milo,

Thanks for the reply regarding taking out the undermount sink. If done correctly, what is the potential of cracking/damaging the granite?

Also, have you ever heard of instances of the chemical odor I described in previous posts? I doubt that it is the epoxy/silicone/etc. given the amount of time since the installation of the sink (7 weeks). We think it has something to do with the sound proofing material on the ss sink.

Regards,
Stan

I am going through this now, my sink cracked after a year of service, and I am replacing it. This is a ceramic sink under granite. I used a putty knife to cut through the silicone holding the sink in place. I just wiggled it in at one spot and worked my way around the sink. It took a while, and a bit of effort, but the granite is still intact! Unfortunately, the white of the replacement sink is much darker than the original sink (differences in manufacturing batches I guess) so I am sending the old one back to the manufacturer to chase down a closer match.
My question on re-install is this - do I have to remove ALL of the old silicone to mount up the new sink? I scraped most of it away with a chissel, but there is still some remaining residue. Will the new sink adhere well if there is silicone left behind (I've always heard to make sure you remove old caulk completely before putting down new caulk in bathroom applications). If I do have to remove it completely, what is the best product/method? (paint thinner, etc?)

Addendum - obviously I had to unscrew the four mounting bolts as well when removing the sink. I loosened them first to make sure I would have some give as I worked my magic with the putty knife, and I put down some moving blankets in the bottom of the sink cabinet to catch anything heavy that might fall. This also made it more comfy when I had to lay under there to scrape off the silicone residue.