Support: What Has to Sit Underneath the Stone
A worktop is only as good as the structure holding it up, and none of that structure is visible once the job is done. The installation notes at countertop installers redding aedreams cover it anyway, because a Redding countertop that cracks a year later almost always failed where nothing was underneath it.
The Cabinets Come First
Every cabinet run has to be level across its length and front to back before anything is set on it. Installers shim as they go, but a shim corrects a few millimetres, not a sagging floor. Stone laid on a twisted base carries stress from the day it goes down and releases it at the weakest opening, usually the sink.
Overhang Rules of Thumb
A three centimetre material will generally carry a ten to twelve inch overhang unsupported. Beyond that it needs help. A two centimetre material needs help sooner. Bar seating on the back of an island, where people lean their weight on the edge, is the usual place this gets tested, and the usual place it is skipped because brackets are unglamorous.
What Support Looks Like
A steel support bracket bolted to the cabinet and hidden under the material is the common answer, and it keeps the underside clear so knees fit. A wooden corbel is the visible alternative and eats leg room. A full plywood deck across the cabinets spreads load on thinner material and is standard practice under some products and unnecessary under others.
Gaps in the Run
A dishwasher, a slide in range or a wine fridge leaves an unsupported span in the middle of a cabinet run. That span needs a rail or a batten across it, and any joint falling over the gap needs proper backing. This is the detail worth asking about directly, because it is invisible at handover and expensive afterwards.
How to Check It Was Done
Open the cabinet doors on the day and look up. You should see clean bearing on the cabinet tops, a bracket or a plywood deck where the material runs past its support, and nothing propped on a stack of offcuts. It takes a minute, and it is the only chance you get before everything is caulked and the crew drives away.