20年的屋頂在一半月renew property Insurance 前， 保險公司要求做Roof Cleaned/or

我們剛收到保險公司的通知，在一個半月後 renew 房屋保險之前，要做 " Insurance company will want either (1) the roof cleaned  or (2) an inspection by a licensed roofing contractor that addresses the discoloration in the inspection report.這房子的roof 有二十年了

（Discoloration is natural, occurs over time, and is usually not indicative of a problem. ）

上來問問這種 Discoloration 的 roof cleaned 如何去做？ 有contractor 能做嗎？

有經驗的房東給些 建議， 謝謝。