Every renovation plan is written before anyone really knows what is behind the walls. Floor plans, 3D renders, material choices, all of it happens on assumptions about a property's condition. Demolition is the moment those assumptions get tested, and it rarely comes back with the exact same picture.
Why tiles come off first, always
Old tiles are usually the easiest thing to remove, and also the least reliable indicator of what is underneath. They can hide poor installation, damp, uneven surfaces, or simply outdated materials that were never meant to last this long. There is no way to know the real condition of a floor or a wall until the old finish is gone.
This is why tiles are always the first thing to go on any renovation, before any layout decision is finalized or any material is ordered. It sets the honest starting point for everything that follows.
The wiring you cannot see until you open the wall
Electrical systems age in ways that are invisible from the surface. A wall can look perfectly fine while the wiring behind it is decades old, no longer up to current safety standards, or simply not built to handle the load of a modern kitchen or air conditioning unit.
On a recent project of ours in Puerto Rico, in the south of Gran Canaria, this was exactly the case. Once the walls came down, the electrical system turned out to be in very poor condition, and the only real solution was a full rewire, brand new from scratch. It is one of the most common discoveries in older apartments on the island, and one of the reasons a proper inspection during demolition matters as much as the design phase before it.
Plumbing: sometimes the good surprise
Not every discovery during demolition is bad news. Plumbing systems, when they were installed correctly the first time, can hold up well for decades with only minor updates needed. On the same project, the existing plumbing was found to be in good condition, and only small adjustments were needed to accommodate a new dishwasher position in the kitchen.
It is a reminder that demolition is not only about finding problems. It is about finding out, one way or another, exactly what you are working with, before any final decision gets made.
Why this matters more than it seems
A renovation plan built on assumptions can still work out, but a renovation plan tested against reality is far more reliable. Discovering an issue during demolition means it gets solved before new materials are ordered, before finishes are chosen, and before a budget is finalized around numbers that might not hold.
This is why demolition is never treated as just a first step to get through quickly. It is where a renovation plan either gets confirmed or corrected, and it is always better to know early.