Nothing in this chapter shall prevent the restoration, rebuilding or repairing of any nonconforming use, which structure has been damaged by fire, acts of God or any act of a public enemy, subsequent to the effective date of this chapter, provided that such restoration or construction is commenced within six months after the destruction and is completed within one year of the date of destruction. For any structure containing a nonconforming use which is destroyed, by any cause, to an extent exceeding 75% of its fair market value, as indicated on the latest assessment records of the Town of Gates, the future structure or use on the site shall conform to this chapter.