Developers have applied to council to modify existing plans for a mixed-used development at No 10 Thomas Street, hoping to add to the height of the building and significantly increase the number of residential units and parking spaces already approved.

Under the proposed changes the complex, to be built on the former Crown Carpets site, would house 25 units instead of 15.

The number and size of the units proposed in the initial development were revised to adequately "reflect current market requirements and to ensure the economic viability of the site", the modification application read.

As a result, a number of three-bedroom apartments - as well as a two-level, five-bedroom penthouse - were replaced with mostly two-bedroom units.

"This revised unit mix seeks to more appropriately cater for market demand in this location within the Wollongong City Centre," the application read.

Other proposed changes to the development include increasing the number of car parking spaces from 21 to 31, and providing additional motorcycle and bicycle spaces and basement storage.

A lap pool has also been added to 213.9 square metres of communal space provided on Level 2.

The modification application proposes to increase the overall height of the building by one storey to accommodate the changes, allow for higher ceilings and "improved built form".

The eight-storey building would comprise of basement parking, 52.7 square metres of commercial space at ground floor and seven storeys containing two one-bedroom units, four three-bedroom units and 19 two-bedroom units.

The site, which is zoned for mixed use under the 2009 Wollongong City Council Local Environmental Plan, sits on the northern periphery of the city's CBD in a "transition area" between commercial and residential areas.

"It is considered that the modified development is an appropriate outcome for the site given the anticipated future character of this precinct as detailed within the Wollongong [Development Control Plan] 2009," the modification application read.