The Hutt City Council has quadrupled its heritage listing properties but the owners are yet to be informed.
The 120 council properties added to a heritage inventory obtained by Radio New Zealand include the TVNZ Avalon studio.
The council says the new properties cover buildings from the 1880s to the 1990s and were identified in a process which began in 2007.
The listing will place restrictions on what owners can do with properties, and though the council says the list is finalised, it has yet to make the inventory public or inform owners.
In a statement, Hutt City Council chief executive Tony Stallinger says the first round of consultation about the list is scheduled for early October.
The list will not come into effect until the District Plan is signed off.
The inventory also includes a bus stop, boatsheds, and school and polytech buildings.