ResGuard is a very simple plugin, which allows you to set main world (by default "world"), and restrict block placing/destroying outside of residences. Players will only be able to do so inside of residence. It does not matter, if that residence is theirs, as residence handles that for you. I made something similar before, but never released it. Now I'm giving it away. I will fix any bugs, and will implement features.
In config, you can change deny message, and main world.
Purpose? Having ungriefed landscape and separate worlds for mining and building.