Tile roofs with a #30lb.felt paper base and a #90lb. hot asphalt installed underlayment system is installed and the tiles adhered using mortar add extra weight to the system. During hot months the roof temperature rises above 160 degrees softening up the asphalt adhesive. With the extra tile weight without fasteners to hold the tiles to the deck cause the roof system to slide, especially on high-pitched roofs. The image to the left shows tiles sliding off, evident by looking at the perimeter edge. There is no way to repair this issue. However, it is a sign that replacement is near.