I have a marble vanity top and I'd like to install an undermount sink. How do you go about mounting the sink to the underside of the vanity top? The underside of the vanity doesn't have any provisions to mount the sink to, no screw holes no nothing. Surely it doesn't just get glued to the vanity top, is there hardware that comes with the sink or do I have to buy that seperately?

 

Many undermount sinks are secured with an adhesive made especially for the sink/countertop material. The sink is supported until the bonding agent cures. A seal of silicone is also applied to prevent leaking. Drilling marble can be tricky. High chance of breaking/cracking the marble. I am not saying you cannot do it, but, you will be taking a chance. You can check on mounting hardware where you buy the sink. Good luck.

 

An undermount sink should come with mounting clips. This set includes some expansion anchors. You drill the approriate hole in the underside of the top, insert the anchor, then the stud for the mounting clip/

If your top is the cultured marble, it is easy. Just use some kind of stop on the drill bit so you don't go too deep!
If your top is actual marble, I would have a stone craftsman do it.

 

Mount the sink to the vanity, not the countertop. My kitchen sink is supported by 2X4's. My MBR sink is supported by 2X2s.

Install the sink before you install the countertop. Temporarily install wood supports across the opening (perpendicular to the front. Put the sink in place and move the supports as needed to get the sink positioned correctly. Once you determine where to put them, permanently attach the supports. Make sure the sink ends up a hair (1/16") below the top of the vanity. Fill any gap between the sink and te countertop with caulk.

You may have to scratch your head a little to figure out how to secure the supports dpending on your setup. I ended up adding a thicker cross piece in the back of the vanity. I used pocket screws to hold the supports in place.

 

majakdragon - what's the adhesive called and where would I get it?

594tough - it's natural marble about an inch thick. I'd really rather not try drilling into it if you know what I mean.

Wayne Mitchell - That was my first thought on how to mount it, I just didn't know if that was correct. I'll be making my own vanity so it shouldn't be that difficult.

Basically, I just want to know how the pros do it.

 

72blazer - my kitchen undermount was done by the granite installers. I copied them when I did my vanity sink.