During overhaul, a rekindle can occur even if what percentage of the fire is extinguished?

During overhaul, a rekindle can occur even if 99% of the fire is extinguished because embers or hidden pockets of heat can still exist within the materials that were not completely cooled. Firefighters must thoroughly check for these remnants of fire, particularly in areas where heat is not visibly apparent, such as in structural voids, under carpets, or within walls. It's essential to utilize tools like thermal imaging cameras and manually disturb materials to ensure that any potential fire source is adequately extinguished. Even with a high percentage of the fire put out, the remaining one percent could still be enough to reignite if not properly addressed during the overhaul process.