The $3 million, twin-level annex will adjoin P Block, which was constructed in 1997. The rest of the school occupies the former Dunedin North Intermediate School buildings on the same Albany St site.
Head of school Bridie Lonie said she was looking forward to having around 225 art students together again.
"This building enables us to take students back . . . from two unsatisfactory sites elsewhere. It means we will be a single community again."
The extra space would also allow the school to deal with increased student enrolments, she said yesterday.
The annex, expected to be completed in February in time for the start of the 2009 academic year, will have flexible studio spaces upstairs and a large lecture theatre and spacious gallery downstairs.
It will also be the school's "front door", with a new main entrance leading out on to Reigo St.
The gallery was a first for the polytechnic, and a welcome addition for students who needed to learn how a professionally run gallery worked, Ms Lonie said.
"It has been designed to professional standards with appropriate storage, which will enable our students to achieve a higher level of professional practice . . ."
The gallery would be open to the public and would show the works of students and outside artists, she said.
The art school annex is one of two major projects part-funded by a capital works grant from the Tertiary Education Commission.
The other is a $4 million revamp and extension of the student centre in Harbour Tce to enable the catering and hospitality school to be relocated from its present site in Tennyson St, near Otago Girls High School.
The target completion date for that project is June.
