How to raise sagging countertops?

shims?calk?good-luck!

If you're looking to cover, not repair, a small strip of quarter round moulding should cover it!

This does not look as if there is any caulk in there to keep water from getting in and destroying the particle board substrate of the laminate countertop. Particle board has no defense from water.

Replacement is the best choice but if you can get under the cabinet and behind the sink to jack the countertop up a bit and put a 1"x2" or 3" across to hold the countertop up, screw it to the wall studs. That should fix the problem for now. Put some silicone kitchen and bath caulk along the length of the backsplash where it meets the counter to keep water from flowing back in there.

My last house was a 1995 manufactured home and I was constantly surprised by the little shortcuts they took. There should have been support across the back of the sink and while building it would have taken so little to do it right.

I would just caulk it with a beige that is similar to your surface.

I would empty cabinet below, and shine a flashlight up to find the metal clips that hold it up, and see if they are loose. You can try just screwing them back in but if the hole is getting strips, you may have to replace the screws with the next fattest size up (not longer) to bite into the substrate. Then maybe run a bead of clear silicon caulk in there to prevent water infiltration.

The weight of the sink and lack of bracing underneath has caused them to sag. Don't caulk, quarter round the gap. They will sag more. There are no "clips" that hold the countertop up. Get under the cabinet where the sag is. Measure the height against the wall from the floor of the cabinet to the underside of the countertop. Cut some 1x2 boards about 1/8" to 1/4" longer than your measurement. Place the boards under the countertop and the cabinet floor against the wall and gently pound them to raise the countertop. If the boards are a little to tight just trim a little off one end. Once the gap is closed then you can caulk the corner seam.

Thank you all. Good info.

If a countertop is sagging, it can be raised by shimming it up from underneath. Here's how to do it:

1. First, remove any items on the countertop and unplug any appliances underneath it.
2. Locate the supports for the countertop. These may be brackets, screws, or blocks of wood that are holding the countertop up.
3. Measure the distance between the bottom of the countertop and the top of the supports.
4. Cut shims to fit between the bottom of the countertop and the top of the supports. The shims should be the same thickness as the gap you measured in step 3.
5. Place the shims between the bottom of the countertop and the top of the supports, using wood glue to hold them in place.
6. Repeat this process at each support until the countertop is raised to the desired height.
7. Once all of the shims are in place, allow the wood glue to dry completely before replacing any items on the countertop.

If the sagging is severe or if the countertop is not properly supported, you may need to enlist the help of a professional to repair or replace the countertop.

Caulk would seal that and it is water proof also.