Does the property order supervisor agree that it is illegal for the owner to expand the basement?

Generally speaking, the basement expansion needs to go through legal examination and approval procedures, otherwise it is an illegal building and will be forcibly demolished.

You need to go through the examination and approval formalities with the planning department first. After approval, the planning drawings will be submitted to the Housing and Construction Bureau, which will organize experts to conduct technical audit. After the safety assessment report is issued by the housing construction department, the construction can only be started if it is qualified.

If the owner's unauthorized expansion of the basement violates the property service contract or laws, regulations and management regulations, and the property service enterprise requests the owner to bear corresponding civil liabilities such as restitution, cessation of infringement and removal of obstruction, the people's court shall support it.

Unauthorized expansion of the basement may also infringe upon the rights and interests of other owners, and should bear the tort liability in the Tort Liability Law.