Quartz countertop seam strength

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I have a 108" section of 26" deep counters. From left to right, starting at the 39" mark, there is a 48" gap for a wine fridge and bar fridge. Then there is a 21" cabinet on the right side.

Had quartz countertops installed and they used two pieces. Problem is the seam is over the 48" gap. 1st section of counter is about 85" and 2nd section is 23". So the seam is floating in the far right side of the 48" gap instead of spanning the gap. Installers said they should have had the 23" section on the left side instead to avoid this. They said it will work the way it is and there won't be any strength issues.

There is a 1×6 running the back wall of the 48" gap for extra support so it's not completely floating. Structurally, do you think this will indeed be fine?

I'm holding a pen where the seam is.

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Best Answer

Absolutely not! Although the seam has been sealed with an adhesive and coloring compound, it provides little flexural strength. Despite the back support, and with little to support the span between the left and right side of the countertop, it will easily break, probably with little more than body weight. Again, the "adhesive" is just a waterproof binding agent for colorant to fill the seam and is definitely NOT something to rely on to keep your countertop from breaking! I would at least add support from below using low-profile 4"X 6" angle steel on both sides: bolted to your cabinets and glued to "quartz".