If zoning or codes change while I own a property, do the changes automatically apply to my property?

Can a city change my property zoning without my permission?
Yes, a city can change your zoning classification without your permission. Legally speaking, zoning is an exercise of what is known to be police power. It does not happen often, and we’re not saying it is a fair practice. But it is possible.
“Police power” is used in the sense that a city’s general powers under state constitutions can do what they think is necessary for general safety, health, and welfare.
The most common case of rezoning is when a property owner, or a future land purchaser, asks for a more advantageous classification. In many cases, this is called a rezoning petition. 
Usually, cities do this when they have some kind of policy goal to maximize. For instance, they might have decided that a specific part of town needs more or less residential density (which means housing units per acre). However, If the rezoning makes your property less valuable, this could be a downzoning. You might want to research that idea.
Will zoning amendments negatively impact what you can do with your property or your ability to refinance, enlarge, or sell it? Can You Be “Grandfathered” into the Old Zoning?
Typically, these amendments increase minimal dimensional requirements, or they decrease the kinds of uses permitted on the property. These regulations can severely restrict existing owners’ use of their land.
Accordingly, municipalities can often protect the owners from difficulties caused by zoning amendments by “grandfathering” current building lots. The local zoning bylaw may provide tha……