Methods
Non-invasive means we start without demolition. It does not mean we can always finish that way.
Boards want a source without opening walls. Thermal patterns, listening on pressurized lines, moisture readings, and a careful look at the building often get most of the way there. Honesty about limits is part of the visit.
The methods follow the question.
Heat patterns, sound on a charged line, moisture at a surface, and history. Not every tool on every job.
Some assemblies hide the signal.
Tile, foil, and some insulations limit cameras. That limit should be in the note.
A small, targeted opening can be the responsible last step.
That is different from opening a corridor to look around.
Questions people ask
Is this the same as thermal-only scanning?
No. Thermal is one method. It is not a complete investigation by itself.
Will you guarantee no drywall is cut?
No honest visit can. The aim is the least opening that still names the source.