The undermount sink in our recently purchased house has started to pull down from the benchtop, so there is a ~5mm gap and the seal has broken. It's only pulled away from one side but I don't think it will last much longer. It is a manufactured stone benchtop so I'm not sure of the best way to repair it. It seems to have been originally fixed with some kind of thick creamy brown glue that feels soft with some give. Judging by the way the glue has dried with drips running down it was mounted with the bench already in place.
What is the best way to remount the sink? Preferably without removing the entire benchtop first :-)!
EDIT: Added some photos
Under back of sink:
Under front. It hasn't pulled away from here:
Back of sink again. This blob didn't even seem to get put on the sink:
Best Answer
An undermount sink needs to be mechanically supported from below, with brackets or some kind of structure that can physically support the weight of sink. Between the water, dishes, maybe even someone leaning on the sink, and the sink itself, we are talking about a load on the order of 100 pounds or more. So definitely far in excess of what an adhesive can support in this layout. In the absence of proper support, the weight of the sink may be resting on your drain pipes, which they are not designed to support. You need to get and install a mechanical support, either brackets (the sink's manufacturer probably makes or recommends some) or a custom-built wood structure to carry its weight. While you're at it, make sure to reseal the edges using a consistent layer of putty or silicone caulk.