Short Answer
Yes. Water can accumulate within insulation, framing, wall cavities, decking, and trim.
Detailed Explanation
Not all water damage is visible. Water can enter a building envelope and accumulate in hidden spaces — soaking into insulation (which may not show any stain on the ceiling below until it's saturated), running down framing members inside wall cavities, saturating roof decking from below (visible only from the attic), or collecting behind trim and siding. By the time water damage becomes visible as a ceiling stain or wall discoloration, the hidden damage may be extensive — rotted wood, mold growth, saturated insulation, and structural damage. This is why professional inspections include attic examinations, moisture meters, and sometimes thermal imaging to detect hidden moisture before it becomes visible.
Why It Matters
Relying on visible stains as the only indicator of water damage can miss significant hidden problems. Professional inspection can detect moisture before it becomes visible.