LAST night's fire at an historic school building in East Launceston was disheartening, the school's headmaster said.
A bench next to the heritage-listed Broadland House in Lyttleton Street was deliberately set on fire before 9.30pm.
The fire spread to the building, built in about 1850, which is now the administration hub of the Launceston Church Grammar School junior campus.
Quick-thinking residents called the Tasmania Fire Service and firefighters contained the fire to one room, although much of the building sustained smoke damage.
Authorities have estimated damage at $100,000.
Headmaster Stephen Norris thanked residents for notifying the TFS and praised firefighters for their brilliant work.
``It's just unfortunate,'' he said.
``It's one of those things that happens.
``No-one was around; the building and campus were empty.''
Mr Norris said families of the junior campus were notified first thing this morning about the fire.
Building assessors have fenced off the damage, which was a curiosity for pupils during recess today.
Police are investigating and urge anyone with information about the incident to call Crime Stoppers on 1800 333 000.