Mich. Comp. Laws § 259.453
Any airport zoning regulations adopted under this act shall require that a permit be obtained before any new structure or use may be constructed or established and before any existing use or structure may be substantially changed or substantially altered or substantially repaired. All such regulations shall further provide that before any non-conforming structure or tree may be replaced, substantially altered or substantially repaired, rebuilt, allowed to grow higher, or replanted, a permit authorizing such replacement, change or repair must be secured from the administrative agency authorized to administer and enforce the regulations. No permit shall be granted that would allow the establishment or creation of an airport hazard or permit a non-conforming structure or tree or non-conforming use to be made or become higher or become a greater hazard to air navigation than it was when the applicable regulation was adopted or than it is when the application for permit is made. Whenever an administrative agency determines that a non-conforming use or non-conforming structure or tree has been abandoned or more than 80 per cent torn down, destroyed, deteriorated or decayed, no permit shall be granted that would allow such structure or tree to exceed the applicable height limit or otherwise deviate from the zoning regulations.
MCL 259.453