The development, in Duke Street in the centre of the city, includes a main building that varies in height from six to eight storeys and a 16-storey tower. The development will have shops, a doctor's surgery and parking. The flats will accommodate 538 people.
The development was designed by Unite's in-house architects, and all the buildings are prefabricated. The individual modules will be lifted by crane on to the site. Work on site is expected to start by the end of July.
Unite is also involved in a similar key-worker housing project in Bournemouth, Dorset, which is to be built by contractor Waring.
Modular rooms bring down cost while improving quality
The Bournemouth site will consist of a mixed-use development of between seven and 11 storeys, with student and key-worker housing and some office space.
Waring secured the Bournemouth contract after winning a similar £18m project for Unite in Portsmouth, Hampshire. This involved providing accommodation for 743 students.