Campus Services' Jenny Bentley told the Herald the university wrote to several students yesterday informing them of the new offer.
The university had investigated all other options for finding rooms, including hotels, before asking students to consider sharing but there was "nothing available", she said.
An "unprecedentedly high" number of students accepting a place at Katharine Jermyn Hall caused the shortage of rooms, she said.
"We are ... 32 single rooms short, although this situation is expected to be resolved in the coming weeks.
"Historically up to one-third of students withdraw their accommodation application before the academic year starts, so it is normal practice to accept slightly more applications than the number of rooms available."
New Zealand Union of Students' Associations president Linsey Higgins was appalled at the handling of the situation.
"You can't just cram students into rooms like they are cattle," she said.
"Is the university hoping for students to fail and drop out so students will get their single rooms back?"
Victoria University of Wellington Student Association president Jonathan Gee said the situation put a lot of pressure on students.