"If this building is demolished, it will have a significant impact because it is a heritage building, it is in the old town conservation overlay zone, it is on a display frontage street corner and it is a signature building visible to the entrance to the town centre.
"A resource consent application will need to address these factors."
Mayor Hamish McDouall said there was an extensive process to be followed to demolish a building that is listed in the District Plan.
"For such a significant building on such a significant site, I would anticipate a very clear idea of what would be intended in place of it as well as other conditions that would be required to permit demolition," Mr McDouall said.
"I've talked to people looking for exactly that type of building to move in to - it's not a building without charm, with those lovely curved windows.
"Just last week academics from Massey University held a workshop about solutions for heritage buildings around Whanganui and one of those was 1 Victoria Avenue.
"It is not strategic to bowl it but there are significant hurdles to get to an end point."
Richard Thompson, who chairs the Earthquake Prone Buildings Community Taskforce that provides independent advice to the council, said it was a concern to see any heritage building demolished if there was a way to keep it.
"Those corner buildings are of particular importance to the streetscape, especially buildings over two storeys like this one is," Mr Thompson said.
"It begs the question of why the owner wants to demolish it and what their plans are for the site. It would be preferable to build a development around retaining and restoring as much of the building as possible. The most important parts are the facade and the parapets.
"What tends to happen is that a development doesn't end up being a building of the same height and scale which is important to maintain, especially on that corner."
Mr Thompson said there could be opportunities for building owners to work together on improving their heritage buildings, including sharing costs and resources.
"Strengthening corner buildings can strengthen neighbouring buildings and there could be cost sharing for development," he said.
"There has been some discussion about that but there is no plan of action."
The council has a building assessment assistance fund to encourage owners of earthquake-prone properties to upgrade their old buildings to meet Building Act compliance. The funding assists with the cost of having buildings professionally assessed, but not with detailed design or physical works.
The owner of 1 Victoria Ave was granted $1500 from the council's heritage assistance fund in late 2015.
According to the Whanganui District Heritage Inventory, the building was erected in 1908 for Thain & Co. The architect was T H James and the builder was Nicholas Meuli.
The building, which is in the Old Town Conservation Zone, is listed as being of historic, architectural, cultural and contextual significance. The District Plan lists it as a class B heritage item which is defined as "at a regional or local level it has several high heritage values and/or has good integrity".
The Thain's building was damaged in the 2015 flood, resulting in a number of businesses permanently relocating. However, Minz - Made in New Zealand, a co-operative of local artists and craft people - is moving from its current Victoria Avenue premises to the Thain's building in late August.
