Four appliances attended the incident at the derelict Crown Inn in St Leonard’s Gate on Monday evening.
Crews used the platform to douse the fire in the roof.
A brigade spokesman said: “We don’t have any further details, other than the building is disused. It’s an old pub.”
There are not thought to have been any casualties.
The old Crown Inn is a Grade II Listed building, but has been derelict for at least seven years.
It was built in the late 18th century and was originally two adjoining houses.
It is reported the city council refused developers permission to convert it into student accommodation in 2009 and it has been empty ever since.