These misaligned and failing front and rear sink rails are an excellent reason why the countertop sink rail design detail in the Marble Institute of America’s Dimension Stone Design Manual should be carefully scrutinized.
These seams have failed because the right side of the sink top has sunk by about ¼”. While failure is never good, it’s much better than what might have happened had this fabricator strictly followed MIA Drawing Number 17-D-4, Detail of Spline Joint Reinforcement:
In this case, had there been a stainless steel washer imbedded into the sink rail ends, it would not have failed harmlessly the way the adhesive joints did. The imbedded washer would have remained rigidly adhered to the end of a 5’ long lever, which is the sinking countertop. With the shim below the top on the cabinet at the seam acting as a fulcrum, the imbedded washer would have to blow out through the top, taking a large piece of the top of sink rail with it. Depending on the movement and/or particulates in the stone, this would be a much riskier and more difficult repair if it could be cost effectively repaired at all.
The detail also allows the use of polyester resin to imbed the washer. Polyester resin does not have the water resistance that epoxy does. Having re-adhered failed polyester built-up edges on stone sink rails, I use epoxy or methacrylate for repairs in wet areas. Fabricators should do the same.
Speaking of polyester, I also have found it to be inappropriate for bedding cold steel reinforcement rods in tops. Here, the failed rear seam has allowed water to penetrate, rust the reinforcement rod, and split the stone. Fortunately, it’s imbedded back far enough to be covered by the backsplash. The “rust” on the deck is polyester; the rod remains in place, and the tip is visible.
I’ve remade sink rail seams many times, and I’m glad when they’re wide enough to allow me to use my Japanese pull saw with the thin blade to remove failed adhesive. This washer detail would decrease the area I’m able to decontaminate by at least 25%. Can you imagine hitting a stainless washer while you’re drilling a faucet hole? I always ditch this detail.
Years ago I met a guy whose business it was to repair broken antique headstones. He never rodded his repairs because if the vandals returned, he wanted the headstones to break at his previous repairs, not make new breaks as rodding would do. You cannot be stronger than the vandals, and you cannot be stronger than physics. You must accommodate each with proper detailing.
When I built my solid surface countertops for our home, we had a freestanding range at the time. When we bought a slide-in style range, I had to make a rear piece of countertop. Although I could have, I did not hard seam the new piece inconspicuously. If the 2” long hard seam fails, you’ve got what looks like a crooked dirty hair at your range after the crack fills with contamination. I cut the rear piece short 1/8”, leaving a 1/16” gap on each end and filled those gaps with color matched silicone which allows the delicate joint to move. It’s still inconspicuous, easily renewable, and will never look like a hair that can’t be wiped up. This is how to accommodate physics.
This sink is leaking, and the clip is rusting because the original installer failed to silicone between the sink flange and the stone bottom. Leaking sinks = exploding rods. Don’t try to unscrew these; place a stiff scraper between the flange and stone then hammer until they fail. The seams cannot be adjusted with the sink in place. I’ll use a Sink Strap to secure it.
The sink is removed, the splash is lifted, and the seam ends are abraded and decontaminated. I’ll put the right top on plane with the left with composite shims which are more dimensionally stable and less compressive than the wood shims the MIA allows. You’re probably not getting a 4” splash containing a duplex receptacle cut-out removed without breaking it. Not a big deal, but try not to let the customers see this, please.
