Boarded up is a common term used to describe a house or building that has been shut up with wooden boards. However, there are several synonyms that make a great alternative. One such word is barricaded, which refers to anything that has been blocked off or sealed. Another synonym for boarded up is sealed, which implies the building has been completely covered and secured. Another option is covered up, which usually means something has been concealed from view by covering it up. Lastly, we have shuttered, which refers to windows or doors that have been closed and locked for safety. These synonyms of boarded up can be used interchangeably with the term to add variety and interest to your writing.