Epoxy sink clips for undermount sink

[Johnm]

I have received much plumbing, heating and general knowledge from this site over the years, thank you. My current renovation project includes Quartz counters and a stainless steel under mount sink.

I am sure the many professionals here have been called on to deal with this sink installation as well as granite counters that have been around for a while.
The most direct advice I can find comes from caesarstone who says that drilling holes should be avoided and recommends epoxy sink clips , a round perforated disk with a bolt to be epoxied to the countertop and provide anchoring and compression to the counter. Many seem to suggest just using the silicone caulk seal as adhesive to hold it in place. ( or to hold the clips ) Meanwhile the popular manufacture of my sink includes clips and a nuts encased in plastic along with drawings and rendered videos of drilling 10 3/8th holes ½ in deep in what looks like could only be quartz but does not say. My countertop provider says they are talking about laminate counter and will not drill the quartz with holes
So I will be using the epoxy but see various reports of how sturdy and long-lasting this is , I can double down and put cables or bars to catch it if it does fail yuck. There are some impressive epoxy and silicon these days but reports of the bonds failing. Maybe just in the case of dirty substrate and new counter will be fine. Am I over thinking this and being obsessive?

 

[Terry]

I see many stainless undermount sinks being bolstered with wood blocking underneath to keep the sink from falling.

And often, that's the repair when a non-supported sink starts to fall.

 

[Sponsor]

 

[Johnm]

I see many stainless undermount sinks being bolstered with wood blocking underneath to keep the sink from falling.

And often, that's the repair when a non-supported sink starts to fall.

Thank you that is the sense I get from what little info I can find along with complaints that the plumber says he has to rip it all out and start again from scratch to install it properly is their a proper way to do this.
Their was a this old house video where the sink clips are rotted and they replace the clip into the brass thread embeded in the granite that is fine. I assumed it would work with " quartz"

 

[John Gayewski]

Build a wood frame (in the cabinet) to drop your undermount sink into. Then counter on top

 

[Jadnashua]

I have a few undermount sinks attached to granite slabs...they're 3cm thick, so maybe thicker than your manufactured stone. The granite fabricator routed some slots under the slab, and provided clips that slid in, then the screw was tightened to clamp the sink in place...so, there are different ways to do this.

In your case, I might try to build a basket to hold the sink in place with some anchors epoxied to the bottom and some adhesive to bond it to the counter material. I'd also call the company that made the counter and ask them how they suggest you mount an undermount sink and probably take their advice.

The issue is, your slab isn't very thick, and the SS will expand and contract at different rates than the countertop material, so you need a resilient material to bond it in place, and a backup restraint in a basket or blocking isn't a bad idea. A sink, full of water and you moving things around can start to get fairly heavy.

 

[Johnm]

The Quartz is 3 cm thick but seems to be much more fragile than I thought and more so than Granite. I do not think anyone will do it with any guarantee it will not break therefore the world uses epoxies or mechanical supports The stone/quartz people say they have nothing to do with installing the sink they just cut the hole. I have ordered some epoxy clips but I am in Canada and its going to be a while.

All brand new cabinets in a kitchen gutted and redone from scratch with great effort. It will be a shame to clutter up under the sink with supports but I will look at it. I had no idea it was going to be this difficult to do this under mount sink in an acceptably sturdy way.
Thanks

 

[John Gayewski]

The Quartz is 3 cm thick but seems to be much more fragile than I thought and more so than Granite. I do not think anyone will do it with any guarantee it will not break therefore the world uses epoxies or mechanical supports The stone/quartz people say they have nothing to do with installing the sink they just cut the hole. I have ordered some epoxy clips but I am in Canada and its going to be a while.

All brand new cabinets in a kitchen gutted and redone from scratch with great effort. It will be a shame to clutter up under the sink with supports but I will look at it. I had no idea it was going to be this difficult to do this under mount sink in an acceptably sturdy way.
Thanks

Just glue and nail a 1"x3" board on both sides of where the sink will sit. Do this on the upper rim of the sink base cabinet. If you need you can go to the hardware store and get metal corner supports for the 1x's. Once you have a board supported on both sides of the sink you can add a front and back support 1x3. No need to clutter anything.

 

[Johnm]

Thanks John , not much cabinet. Corner and sink are open , just stretchers across top no plywood on left side till wall. Was really all designed to hang from counter.

 

[Tuttles Revenge]

The remodel contractor we work with the most always designs their sink installations so that the sink can be removed and replaced without destroying the cabinet if needed. The sinks are held in place either by spreader bars or wood fastened to the cabinetry with screws that are accessible from below after installation. The counter top installers often still epoxy their own clips to the underside and will always silicone the sink to the top as well.

 

[Jadnashua]

If you epoxied some wood to the bottom of the counter, the larger area versus just the anchor of a clip, should give you enough strength to hold your sink.

 

[Storm rider]

You might consider an undermount sink harness, such as this one

https://www.bbindustriesllc.com/hercules-universal-sink-harness-kit.html

 

[Johnm]

So Iwas assuming I would have to mount the sink. I ordered "epoxy sink clips" and cans of the black thick epoxy used in all the videos but even though I paid the profiteers the epoxy was not coming for some time.

I began searching for a local source for epoxies looking for something that was not the stuff at big box stores and found product at a local marine supply in a caulking gun tube that mixed the two parts as it was expelled and had good specs and confirmed with the manufacturer it bonded to the Quartz counter. I do not know why I would doubt that epoxy bonding to quartz countertop would be an issue they seam the slab with it. The epoxy clip bolt attachment to the countertop has holes for the epoxy to squish through and capture the anchor. Epoxy bonding to the steel was not in my mind at the time.

In my fevered DIY homeowner brain I made plans to set anchors make a jig to jack the sink into position after I silicone it and for extra support epoxy the cabinet top wood 1x 4 stretchers to the counter and screw to them to brace the sink as extra support. ( ya I know board across counter and clamp through drain but drain is offset in corner)

I gave the installer the epoxy gun and explained I wanted the counter epoxyed to the cabinet boards around the sink instead of the usual silicon as adhesive and he indicated thats ok and he would do that. They had stated that they would cut the cabinet opening for the sink to fit in. I did not stand over them and watch. After an hour the counters were in and seamed the sink was in and they said they were done and said goodbye.

I looked and thought the sink was silicone in and that the silicone around the inside edge of the sink was less than perfect, it was a flush edge. I was surprised at how much of the cabinet boards had been cut to allow not only the sink but the faucet as well. A small amount of the cabinet top had been left at the corners of the sink that supported it

They had dropped the sink in supported by those bits in the corners and put my epoxy on the sink before putting the counter on! and backfilled the inside edge of the sink with silicone. Pics are attached.

I checked with the epoxy manufacturer and they said their should be no problem with the epoxy bonding with the stainless steel sink!

I had no idea! In all the things i found on the net that bonding a stainless sink to quartz with epoxy was an option. I had seen nothing that mentioned this. I can see that it makes removing the sink more difficult but also more difficult to fall to the bottom of the cabinet. I have been asking kitchen cabinet people about this and been told its just that silicone is cheaper and epoxy is used sometimes. I learned that epoxy is used to bond stainless steel instead of welding because welding heat makes the steel blue and that there is a category of structural epoxies for metal.
I added a couple of epoxy clips on one side of the sink and on the other side it was close enough to the cabinet to screw a 2x4 cleat from the dishwasher bay side.

I now feel confident this sink will not fall to the bottom of the cabinet.