In these sites you can find English translations of summaries of court cases and instructions in newer texts.
Also you can find translations of laws in Finlex.
Some helpful links :
Housing transactions act / asuntokauppalaki which refers to selling and buying new and old apartments from a housing company (asunto-osakeyhtiö, asoy ).
Code of Real Estate / maakaari which refers to selling and buying real estates including a building / house.