Further details of the $200 million expansion of Auckland's biggest mall have been revealed, including that the overall centre will soon cover more than 10ha of indoor floor space and 50 new shops will open.

Plans for the expansion of Sylvia Park at Mt Wellington have already been announced by owner Kiwi Property but Robert McFarlane and David Thornton, architects of The Buchan Group who are designing the changes, took the Herald on a trip this week to explain in more detail how the huge centre would be altered.

While Topshop is shutting on Queen St and Amazon is establishing its first Australasian presence with a big Melbourne warehouse, the architects said Sylvia Park was being significantly expanded.

Changes includes:

• An upper-level extension of 24,000 sq metres or 2.4ha will open in the next two to three years;

• It will run from the Southeastern Arterial Motorway end to The Warehouse end near the Southern Motorway; 

• About 50 new shops including some not yet in New Zealand, will trade in the new area; 

• The new structure will be a galleria-style atrium, partially glazed, flooded by natural light; 

• That galleria will have voids opening views to the ground floor; 

• At least one new department store will open in the expanded mall; 

• That department store will be towards the southern end and two storeys high;

• New galleria shops on level one will have a strong fashion focus;

• Construction of the new outdoor dining lane, The Grove, will finish in the next three months; 

• That $9.1m project will offer more alfresco dining;

• Six new restaurants, a new town square, landscaping and a signature dining pavilion are planned to open before Christmas; 

• A 50m-long canopy above The Grove will automatically unfold at the first spots of rain; 

• That canopy to protect diners has been built in sections, constructed of Teflon-coated material and is already up and ready to operate; 

• More robust and durable paving is being laid in the outdoor dining precinct; 

• Mexico and Better Burger restaurants opened recently;

• Work is progressing on new $80.2m 10-level office block, bringing hundreds of more people to work at the centre.

McFarlane showed plans of how the new galleria-style expansion would look and revealed how the roof of the car park would be removed soon and the 50 new shops and department store space would be constructed. Most of the existing structure was robust enough to take the extra level, the architects said.

Shoppers visiting the centre in the next two to three years while work is under way would probably not be aware of the huge construction changes because a temporary roof would be in place, McFarlane said.

The existing roof of the main mall would be removed some time after Christmas, he said. 

Thornton said international retailers would come to New Zealand to lease space in the galleria and he expects at least five in the expanded mall.

"We're looking to achieve an international style of design in line with some of the biggest shopping centres in Australasia," Thornton said.

Centre manager Lauren Riley said Sylvia Park included the retail centre opposite on the Mt Wellington Highway where shops include Torpedo 7, Spotlight and PK Furniture. When all the retail space in the two centres was combined, the entire centre would cover 88,529sq m of floor space, she said.

However, when the main centre is expanded with the new 10-level offices, Sylvia Park overall would be more than 100,000 sq metres or 10ha of indoor floor space, Riley said.