Ask your municipal authority In Denmark
If you want to convert the outside of your house by building an attic or a balcony, for example, or if you want to erect an outbuilding or build a carport, you must comply with a number of laws and regulations. Contact your municipal authority before you begin.
Cooperative housing members must inform the board
you are a member of a cooperative housing project, you must find out whether cooperative housing society regulations contain special restrictions before commencing conversion work.
Tenants must agree on changes with the landlord.