Do I Need Glue For My Under-mount Sink - Plumbing - DIY Home Improvement | DIYChatroom

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Plumbing


Thread Tools Display Modes
Old 02-03-2014, 07:55 AM   #1
Join Date: Oct 2006
Posts: 188
Rewards Points: 173

Do I need glue for my under-mount sink

Dear experts,

I need to replace my broken under-mount bathroom sink. The existing one is held under the granite top with metal clamps. But also it is glued to the granite top. Or maybe it is some caulk. My question is whether I need that glue or caulk, as I cannot see what it is for. I don't know why I need waterproofing there, as water would never reach the granite top.



Last edited by dpreznik; 02-03-2014 at 11:50 AM.
dpreznik is offline   Reply With Quote
Old 02-03-2014, 07:27 PM   #2
Join Date: Mar 2013
Location: Ohio
Posts: 4,781
Rewards Points: 2,108

Seal the Sink in Place

For most bathroom undermount sinks, all that is needed to mount the sink to the granite is a silicone adhesive. Squeeze a very thin line around the sink cutout on the underside of the granite. The weight of the sink will compress the adhesive slightly, making it spread out, so a thin line is all that is needed. Lower the sink into place, upside down on the countertop's underside, then lift it straight up again. This will cause the adhesive to pull away in small "strings" from the counter to the sink. The air hitting these strings will make the adhesive bond stronger. Lower the sink back into place and leave it undisturbed for 24 hours to dry.

Using Mounting Clips

The majority of undermount sinks only need adhesive to bond them to a vanity counter, but some large or oversized bathroom sinks will also use mounting clips. This small metal clip fastens on posts to both the sink and the granite top. Epoxy is used to attach the posts to both materials, then the clip is slipped over them and a small nut is fastened down on each post to hold the clip in place. The epoxy will cure hard enough to fasten the clips onto the posts in approximately 10 minutes, but the clips still need a full 24 hours to dry before the counter is mounted into place.


Ghostmaker is offline   Reply With Quote
The Following User Says Thank You to Ghostmaker For This Useful Post:
dpreznik (02-04-2014)
Old 02-03-2014, 09:12 PM   #3
TotalHomeworx's Avatar
Join Date: Jan 2014
Location: Canada
Posts: 70
Rewards Points: 75

Yes, It's silicone. Buy 100% silicone caulking not siliconized latex.
TotalHomeworx is offline   Reply With Quote
The Following User Says Thank You to TotalHomeworx For This Useful Post:
dpreznik (02-04-2014)
Old 02-04-2014, 06:22 AM   #4
Join Date: Oct 2006
Posts: 188
Rewards Points: 173

Thank you gentlemen,

Though I still don't understand why one needs silicone if there are clamps there. Also, how could weight of the sink compress the adhesive, if the sink is under the granite top, and I cannot turn the top over, as it is already installed. I am just going to replace a broken sink.
dpreznik is offline   Reply With Quote
Old 02-04-2014, 06:41 AM   #5
Join Date: Nov 2011
Location: Hartfield VA
Posts: 34,590
Rewards Points: 14,312

How do you think you your going to seal water out between the top and the sink without the silicone?
When posting in forums, letting us know your location will help others give better feedback/advice/solutions to your questions
joecaption is offline   Reply With Quote
The Following User Says Thank You to joecaption For This Useful Post:
oh'mike (02-04-2014)
Old 02-04-2014, 06:49 AM   #6
DIY staff

Join Date: Sep 2009
Location: Kane county,Illinois
Posts: 25,728
Rewards Points: 7,174

The silicone serves several purposes----it's an adhesive and will keep the sink stable if it gets bumped or a clip fails--

The silicone keeps crud from getting into the gap between the counter top and the bowl--eliminating a place for mold to grow.

Also keeps the cabinet dry--while you may not over fill the sink, it is likely that someone will splash water onto the seam---


New members: Adding your location to your profile helps in many ways.--M--
oh'mike is offline   Reply With Quote
The Following User Says Thank You to oh'mike For This Useful Post:
dpreznik (02-04-2014)

bathroom sink , under-mount

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY Camera Mount divedaddy03 Tools 0 04-06-2013 01:05 PM
top mount sink wont seat carole2cd Plumbing 2 06-20-2010 12:34 PM
Direct mount sink pump recommendation kornfein Plumbing 0 04-29-2010 11:49 AM
do i have to remove old adhesive glue on wall for new ceramic with glue? Limit54 Tiling, ceramics, marble 2 03-01-2010 10:12 PM
Sink Depth dilemna Yippee Plumbing 9 01-01-2008 12:25 PM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1