Fire and Emergency NZ crews were called to the blaze on Shands Rd, near Amyes Rd, in Hornby about 11.30pm on Wednesday.
A FENZ spokesperson said crews from the Wigram, Spreydon, Ilam and Christchurch City stations attended.
The fire was extinguished by about 12.10am.
A scene guard was stationed outside the building overnight and a fire investigator was at the scene on Thursday morning.