A code violation and warranty exclusion on all asphalt based roof systems, ponding water is when water sits on a roof for more than 48 hours without being evaporated or running off naturally. Water ponding breaks down asphalt, which is an oil-based product. Think of potholes in the road. Or, imagine a pot of boiling water when cooking. If oil were added, it would stay on top of the water. On a roof the opposite effect happens. The oil is trapped at the bottom and due to it’s natural properties, tried to rise to the top causing oil migration. Oil migration when the oil and waterproofing properties of a roofing product are pulled out, causing the roof system to break down.