I had quartz countertops installed in my new kitchen yesterday along with a Blanco silgranit undermount sink. Aside from some minor issues, everything had seemed to go pretty smoothly. When I went to start getting the sink ready for the plumbing install, I noticed that there were some rather unattractive pieces of scrap wood that had been hastily screwed into the sides of the cabinet walls. Looking closer, it looks like this is part of what is supporting the sink from below. Is this considered an acceptable practice or should I have them come back and fix it? It's pretty obvious even when quickly looking underneath the sink. I can also confirm that metal brackets were used to support the rear of the sink and were bolted to the quartz directly.
I have to say that those scrap pieces of wood look like rather shabby workmanship to me. I would definitely have the installers come back out and clean up that mess.
If you have any chance to hold up any due payments you should do so until this is corrected.
I cannot say whether this is an overall acceptable way to support the sink but if it is expected that some support piece is to be attached to the cabinet there are surely neater ways to achieve this than a couple of splitting 1x2's stuck in there with drywall screws.