Undermount sink issue

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tailgunner

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Had the undermount stainless sink separate from the granite countertop this morning . Luckily there is a pull out garbage can under there to help support the weight of the disposal. I am looking for ideas on the best way to reattach the sink. Would I need to disconnect the disposal ? I assume I would need a good epoxy to reglue it ?
Thanks in advance for your input
 

Jamesplumbing06

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You need a granite forum. But yeah turn off valves in cabinet and disconnect the plumbing for disposal. Measure the inside width of cabinet. Cut 2 - 2x4 that length. Remove adjacent drawers. Get sink back in position then insert 2x4’s under rim of sink and screw from each drawer opening to your 2x4. I use “lexel” or “through the roof” hand tube caulk and seal the seam between top and sink. Hook your disposal back up.
 

Mikey

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Most undermount fixtures come with clips used to hold the fixture in place. Most installers throw the clips away and just use a good adhesive caulk. I've always had doubts about the caulk, but after having had to remove a caulked-in sink, I was a believer. But, the caulk left over from last year's base mold install won't do. Moen recommends 100% silicone caulk, but there are several brands out there which specifically target undermount applications. The basic process is well documented in YouTube videos.
 

Mitchell-DIY-Guy

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I’ve had this professionally done twice recently in two locations with different sinks and contractors. Both used some two-part goop-a polyester or epoxy compound—definitely NOT caulk or silicone.
 

tailgunner

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There were no clips on mine . Just pieces of wood epoxied in place. I plan on using these, looks like a good solution.

1590398414492.png
 

Dan the Plumber

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All the granite tops I've seen were glued to a plywood base with the sink sandwiched between the wood and the Granite. The sealant was put between the sink and the granite but only as a seal. The weight of the sink was supported by the plywood. You happen to have a stainless sink but don't forget others might have a cast iron one. Full of water a cast iron sink could weigh well over a hundred lbs. Best listen to what JamesPlumbing has to say. Clips are usually for bathroom sinks
 

Jamesplumbing06

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Just think. Epoxy is why your in this mess. Epoxy is holding the scrap pieces of wood to anchor the sink 🤔🤔. Epoxy is a no no. Stay away from trusting epoxy or any kind of caulk, glue. Build a structure to hold that sink in place. Then seal with your choice of caulk. Even good granite guys will tell you the same thing. My father in law is a granite and tile guy. He lost faith in epoxy long time ago.
 

Mitchell-DIY-Guy

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Actually best to follow manufacturers recommendations. This photo is of the prep work done for a Ruvati apron front farmhouse kitchen sink in SS. They call for a supporting frame so I built one out of hardwood and mounted to the base cabinet. Provides full support. This is actually a flush mount installation. Yes the cabinet is packed underneath. The disposal, an air switch for same, an RO drinking water system, a detergent dispenser, faucet, plus the normal plumbing stuff.
 

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tailgunner

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That looks like a great way to go, but how do you fasten the frame to the cabinet sides. The side is flimsy and thin, and doesn't seem to allow a good base to attach the frame. Bob
 

Mitchell-DIY-Guy

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@tailgunner what you cannot see in the photos are four uprights made of 1x3 poplar. These are at each corner of the cabinet. They support another 1x3 on R and L sides, providing “rails” on either side. The frame sits on these rails. Everything had to be made to fairly tight tolerances. Here’s a view of the right side; the black box is the air switch. Unfortunately the forum rotated the photo.
 

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Dan the Plumber

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Yes, or about 10 pounds per clip. Or about 1.2 lb/sq inch load on the adhesive used on a typical sink (I used a Kohler K-5540 as an example).
The water alone in a K-5540 would weigh 188 lbs. in a K-5950 Cast Iron sink the total would be 230 lbs. And thats without somebody pressing down to scrub a pot.
 

tailgunner

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First of all , thanks for taking the time to take the photos and posting, your help is very much apprciated. I see what you did with the vertical 1x3's . But what about attaching those to the thin walls of the cabinet?
 

Jamesplumbing06

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Screws and a second sandwich block on opposite side of cabinet walls. A granite guy will go a long way. They aren’t terribly expensive.
 

Mitchell-DIY-Guy

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But what about attaching those to the thin walls of the cabinet?
@tailgunner: Cabinets are ½” plywood box construction. All the 1x3 poplar was pinned to the cabinet sides with 1.25” brads from a pneumatic nailer. All the force on this is compression from the weight of the frame (negligible) and sink. The weight comes from the disposable unit on the sink, plus any water if you fill the sink. There’s no lateral forces.

The sink manufacturer, Ruvati (super quality sinks, BTW, at superb prices) describes a similar frame and support system but made of conventional 2x4s. That would have taken up too much room in a very crowded under-sink situation. In fact if I did something out of 2x4 I don’t think there would have been room for the disposal or my RO system. I believe I measured for all of that and chose a more elegant solution out of hardwood. It worked fine. That sink is very deep. Another thing you cannot see is I put a dense foam cushion on the top of the frame (1/16” thick self stick foam sheet from a craft store!) so the sink wasn’t directly on the wood.

Backer blocks on the outside of the cabinet were not really practical nor necessary. Cabinet was already installed. Granite installed. Access to the outside sides not practical.

Granite installation company specifically stated “we just install the granite” and set the sink. Any plumbing attachment or framing must be done prior to granite installation. No way they would have done this.

BTW my Ruvati was (sold the home in April) every bit as nice and as well made as the aforementioned Kohler K5540. (Mine was an apron front model, however) The Kohler costs, retail, $1,000. A nearly identical Ruvati, with all those accessories such as cutting board, colander, drying mat and grid, about $380. Ruvati is high quality 16 gauge SS; Kohler is thinner 18 gauge. Both Kohler and Ruvati have good quality sound deadening. I believe both are made in China. I actually paid a whole lot less than that pre-Chinese import dancing that the current administration started. It's still a deal. I could not have been more pleased with the Ruvati...I was so happy with the quality that I replaced the crappy builder grade plastic (Ugh!) laundry room sink with a Ruvati SS model.
 
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