A renovation splits into what you can see and what gets covered. The visible part can be redone at any time — repainted, re-covered, new fronts. The covered part can only be redone together with the wall.
Electrics. Cable size for the hob and the oven, a separate breaker for each line, sockets behind built-in appliances. Ask for photos of the walls before plastering — afterwards you will not find a single cable.
Water. Supply points for the sink, the dishwasher and the filter. The shut-off valve must be reachable without dismantling the cabinet: one day that saves the flat below yours.
Ventilation. The extraction duct and its diameter. Flexible ducting squashed flat under a cabinet halves the airflow, and no extractor hood will make up for it.
We photograph every wall before plastering and hand the pictures to the client. This is not a formality: a year later, when you need to hang a shelf, you will know where the cable runs.