Before tile roof adhesive and screw fasteners, tile was installed using a single patty of mortar cement placed on the roof and the tile imbedded into it. Although installation techniques required each tile to be submerged in water prior to installation, this was rarely ever followed. Each tile was set in place and left to dry. Over time and movement the tile breaks loose from the mortar and does not re-adhere. The temporary solution is to lift each tile and spray roof tile adhesive under it to create a new bond. However, this is labor intensive. If not repaired, the roof tiles may easily dislodge and become airborne during a high wind event.