Need help doing a DIY repair on an undermount bathroom sink.
November 29, 2024 12:31 PM Subscribe
I have an undermount bathroom sink that was unfortunely installed with only gobs of caulking affixing it to the vanity. The basin has fallen and I am having trouble finding the right thing to fix it.
Sadly, replacing this awfully designed sink basin with something new is not an option. It seems clear that I need something to hold the sink basin up from below. Currently, I'm using a stack of old textbooks, but something tells me that isn't a good long-term solution. I got these sink clips, but they aren't quite the right thing. They seem to be designed for sinks made of thiner material, like metal. My bathroom sink is ceramic. These clips seem like they might work, but I'd like to get advice from people with more fix-it knowledge than me before I order something else I will never use. Also, any advice or other solutions are welcome. I am not a professional repair person, I don't have specialized tools, and I'm trying to do this somewhat cheaply.
Here are some pictures of the underneath of the sink in question.
Sadly, replacing this awfully designed sink basin with something new is not an option. It seems clear that I need something to hold the sink basin up from below. Currently, I'm using a stack of old textbooks, but something tells me that isn't a good long-term solution. I got these sink clips, but they aren't quite the right thing. They seem to be designed for sinks made of thiner material, like metal. My bathroom sink is ceramic. These clips seem like they might work, but I'd like to get advice from people with more fix-it knowledge than me before I order something else I will never use. Also, any advice or other solutions are welcome. I am not a professional repair person, I don't have specialized tools, and I'm trying to do this somewhat cheaply.
Here are some pictures of the underneath of the sink in question.
Response by poster: Interesting question. The counter is about an inch thick, and is made of what I'm guessing is "engineered stone" but seems fairly light and plastic like. It sort of looks like marble, which I'm guessing is the point, but is most certainly not the real thing.
posted by firemonkey at 1:11 PM on November 29
posted by firemonkey at 1:11 PM on November 29
This is how my sink (ceramic undermount into quartz) uses very similar shaped clips (professionally installed), only two of them, one on each side. It will probably work for you as long as you can tighten them so that they’re applying pressure inward. i think your main issue is that your installation used a bad adhesive or poorly applied. It looks like This Old House has a good video.
posted by supercres at 1:13 PM on November 29
posted by supercres at 1:13 PM on November 29
You could replace your stack of textbooks with one or a couple of floor jacks which are designed for spaces 3.5"-6”, if you think your vanity has the structural integrity for it — and reglue, of course.
posted by jamjam at 1:52 PM on November 29
posted by jamjam at 1:52 PM on November 29
I used this product to repair an undermount kitchen sink, and it worked beautifully: Never Fall Complete Sink Repair System.
posted by bluloo at 1:54 PM on November 29 [9 favorites]
posted by bluloo at 1:54 PM on November 29 [9 favorites]
If your countertop is indeed engineered stone, you don't want to be drilling or cutting into it from underneath; the silica dust it releases when you do that is very bad for you. The Never Fall kit that bluloo linked to screws into the cabinet walls rather than the countertop, so as well as being easier to install it's going to be safer.
posted by flabdablet at 6:56 PM on November 29 [3 favorites]
posted by flabdablet at 6:56 PM on November 29 [3 favorites]
I think the clips you linked to would do the job well, in combination with new adhesive to replace the caulking that's falling apart.
The adhesive will probably come in a cartridge that looks similar to caulking, but it's a different product.
Ideally: remove old caulking, clean very well and make sure both surface as free of dust and grease. Apply new adhesive, and then secure with the clips to create a tight seal. The adhesive will most likely be squeezed out towards the inside of the sink from the pressure, so you'll have to remove that and smooth things out with a wet finger. You want a clean, smooth, and waterproof edge between the vanity and the sink, so no moisture can get in there. That might be what happened in the first place and caused the caulking to fail.
Maybe watch a few youtube videos on "undermount sink installations" to get a feel for what to expect.
posted by PardonMyFrench at 5:00 AM on November 30
The adhesive will probably come in a cartridge that looks similar to caulking, but it's a different product.
Ideally: remove old caulking, clean very well and make sure both surface as free of dust and grease. Apply new adhesive, and then secure with the clips to create a tight seal. The adhesive will most likely be squeezed out towards the inside of the sink from the pressure, so you'll have to remove that and smooth things out with a wet finger. You want a clean, smooth, and waterproof edge between the vanity and the sink, so no moisture can get in there. That might be what happened in the first place and caused the caulking to fail.
Maybe watch a few youtube videos on "undermount sink installations" to get a feel for what to expect.
posted by PardonMyFrench at 5:00 AM on November 30
I used the same system as bluloo mentions (or one very much like it), and the sink—in our case, the main kitchen sink—never budged again.
Because of tight clearances in a few spots, I actually had to use the front pieces of one product and the rear braces of another, but both basically worked the same way: by bracing the sink from below by attaching to the rear and side walls of the cabinetry. The solution worked extremely well.
posted by jquinby at 8:03 AM on November 30
Because of tight clearances in a few spots, I actually had to use the front pieces of one product and the rear braces of another, but both basically worked the same way: by bracing the sink from below by attaching to the rear and side walls of the cabinetry. The solution worked extremely well.
posted by jquinby at 8:03 AM on November 30
I wouldn't drill into the benchtop, not just because it's incredibly bad to inhale the dust (it is), but mostly because it's just not necessary. Undermount sinks/basins work perfectly well pretty much indefinitely with no additional support if they are installed correctly. My guess is that the original installer didn't use the correct material to glue the basin in place and that's why it fell. Installers generally only use clips or similar to hold the sink/basin in place while the compound cures and they don't have any permanent role in holding it up.
You need the correct compound to glue the basin back up and a couple of lengths of wood that can be jammed under the basin to hold it tight against the benchtop while the compound dries. Remove the basin and thoroughly clean and dry both the underside of the bench and the top of the basin lip. You need to be thorough and ensure you remove not only all the old compound, but also any soap residue or other 'stuff' that has got into the joint.
When you have everything ready and have done a 'dry fit' to make sure your temporary props are the fight length etc, apply the compound to the top of the basin lip (more rather than less, but don't go overboard), lift the basin up into pace and jam your props in place (you could do this on your own, but two people would be preferable). Don't run water until well after the recommended curing time on the instructions for the compound and leave the props in place for at least a week. The idea is to make sure the compound is completely and thoroughly cured all the way through before it has to take any weight.
As soon as you have the basin fixed in place, clean the excess compound off the inside of the basin. Not essential, but I would mask off the basin and the edge of the benchtop first to make cleanup easier.
posted by dg at 6:00 PM on December 1
You need the correct compound to glue the basin back up and a couple of lengths of wood that can be jammed under the basin to hold it tight against the benchtop while the compound dries. Remove the basin and thoroughly clean and dry both the underside of the bench and the top of the basin lip. You need to be thorough and ensure you remove not only all the old compound, but also any soap residue or other 'stuff' that has got into the joint.
When you have everything ready and have done a 'dry fit' to make sure your temporary props are the fight length etc, apply the compound to the top of the basin lip (more rather than less, but don't go overboard), lift the basin up into pace and jam your props in place (you could do this on your own, but two people would be preferable). Don't run water until well after the recommended curing time on the instructions for the compound and leave the props in place for at least a week. The idea is to make sure the compound is completely and thoroughly cured all the way through before it has to take any weight.
As soon as you have the basin fixed in place, clean the excess compound off the inside of the basin. Not essential, but I would mask off the basin and the edge of the benchtop first to make cleanup easier.
posted by dg at 6:00 PM on December 1
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posted by deadwax at 12:37 PM on November 29