What is the only method to determine there are no hidden fires in a building of ordinary construction?

The method of opening up walls is essential for uncovering hidden fires, particularly in buildings of ordinary construction. Many structural components, such as stud cavities and concealed spaces, can conceal smoldering fires that are not detectable by visual inspection or surface methods. By physically accessing these areas, firefighters can ensure that there are no hidden embers or flames that could reignite and pose a serious threat.

While using a thermal imager, looking for signs of heat, and feeling for heat are valuable tools and techniques in fire investigation and firefighting, they may not always be definitive. Thermal imagers can identify hotspots, but they are limited to what is visible thermally; they might miss cooler areas that contain hidden fires. Observing signs of heat or feeling the temperature can provide indicators, but these methods alone do not allow for thorough investigation behind walls, where fires can smolder undetected. Thus, opening up the wall is the only method that guarantees access to areas where fire might be lurking, ensuring comprehensive safety and risk management.