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Undermount Kitchen Sink Caulking Question

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9.2K views 17 replies 7 participants last post by  ddsrph  
#1 ·
How much caulking should be applied for a undermount sink against granite countertop?

I used DAP Kwik Seal Adhesive Caulk, made it ooze so it was a thin layer between the top of the sink and the bottom of the countertop. After one week the sink fell. I got some "better" caulking apparently Mono Silicone Max. Now I am wondering if I shouldn't squeeze the sh!t out of it and leave a hefty amount of caulking between the sink and the bottom of the counter top? I also got those leg supports from Amazon! But I need to caulk that thing in place for now. Thoughts?
 
#2 ·
Well Marty..... You don't "caulk in" an undermount sink....it has to be mechanically supported...normally/preferred by cabinit framing.... but also by manufacturer clipping systems.

(The caulking around the perimeter of the sink is only a seal to keep splash water out of your cabinet)
 
#8 ·
Sinks are not installed with caulk ... and I personally have stopped using anything DAP a very long time ago.

Not all countertop materials and sink materials are the same. Some sinks are not designed to be under mounted, while some may have both as an option. Still, an ordinary off the shelf product from the big box store is unlikely to hold up a sink with pots & pans, water ... as far as I am concerned.

We have several under mount sinks, they were installed by the countertop crew with a commercial special purpose adhesive as well as received two small " rails " along the left and right lip, to support the sink while the glue was setting and to help support it permanently. They said they do not install without additional supports. I don't recall if they used some kind of anchors and/or epoxied. ( I was trying not to hover too much and it has been a few years ) Then the inward facing gap that we see as the customer was " caulked " with clear silicone suitable for kitchen and baths.
 
M
#12 ·
icerabbit said:
Sinks are not installed with caulk ... and I personally have stopped using anything DAP a very long time ago.

Not all countertop materials and sink materials are the same. Some sinks are not designed to be under mounted, while some may have both as an option. Still, an ordinary off the shelf product from the big box store is unlikely to hold up a sink with pots & pans, water ... as far as I am concerned.

We have several under mount sinks, they were installed by the countertop crew with a commercial special purpose adhesive as well as received two small " rails " along the left and right lip, to support the sink while the glue was setting and to help support it permanently. They said they do not install without additional supports. I don't recall if they used some kind of anchors and/or epoxied. ( I was trying not to hover too much and it has been a few years ) Then the inward facing gap that we see as the customer was " caulked " with clear silicone suitable for kitchen and baths.
Click to expand...
Most of the undermount sinks I've seen don't even have a place to put clips or fasteners.

With any bonding proper prep work is key.

Interesting how different areas do different things.
 
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