In SAELIG there are multiple social classes. These classes dictate how many buildings you own, and are directly tied to your asset value. Asset value is determined by the amount of silver you currently have plus the value of your buildings.
Property Limit: 0
Asset Requirement: 0 Silver
This is the lowest class in the game, these are the poorest of the poor. They usually live in the bunkhouse and have very little money. They cannot own any property, but can rent homes. A lot of the workforce is made up of Gebura.
Property Limit: 3
Asset Requirement: 2000 Silver
This is the middle class in SAELIG. They can own 3 properties. Quite often they will own at least one house, and in some cases they will also own a business. Kotsetla will also sometimes work in jobs for other people.
Property Limit: 50
Asset Requirement: 15000 Silver
These are the high class people, they usually have the most money and own the majority of the rental properties and businesses. Very rarely will you see a Geneat working at someone else's business.
Other than hitting the asset requirement, there are a couple other ways to attain a higher class. You can marry someone of a higher class and you will automatically be bumped up to their class. Alternatively if you inherit more buildings than your current limit via marriage or death, you will be bumped up to the next social class.