The fire, which started shortly before 5 p.m. on Monday, is believed to have been caused by an electrical fault in the cafe area of the games hall block which also contains changing rooms, squash courts, office and equipment storage accommodation.
A member of the community use staff arriving for work discovered the blaze and raised the alarm. When the fire service arrived on the scene the building was well alight and the fire quickly spread into the roof area, which contains asbestos.
Luckily there were no pupils in the building at the time and no-one was hurt.
Two appliances from Kirkcaldy were soon joined by another two and an aerial platform.
But despite the fire, staff rallied together to ensure that the school's annual achievement evening – which honours the pupils' many accomplishments – went ahead as planned, and the school opened as usual to its 1750 pupils the following morning.
The grim task of clearing out the building and assessing the extent of the damage also began.
Gordon Mackenzie, headteacher said: "The damage was extensive and it is anticipated that the school will be without its games hall for a considerable time - possibly several months.
''The cause of the fire is being investigated but I can confirm that it was not deliberate.
"The site is out-of-bounds and until the fire assessor visits we are unable to draw up a timetable of action. When we know the extent of the damage we shall be able to plan ahead.
"It is anticipated that some of the activities taught in PE will be restricted until the renovations have been completed, but we are actively looking for alternative accommodation nearby.
"I wish to recognise the actions of the fire service in dealing with the fire - their professionalism was superb. The police also provided great assistance.
"Since the fire we have been working closely with various services within the Council and we have been equally impressed by their commitment and level of support.
Louise Playford, school estate service manager, said: "We are unable to say what the full extent of the damage is as we have not been allowed access to the building but it appears to be mainly internal fire and smoke damage.
"The damaged building has been made safe and we will be carrying out an assessment as soon as possible."
Evelyn Hamilton, head of centre for Balwearie Community Use this week said she was confident that plans to run summer holiday sports activities for children at Balwearie would go ahead.
"We still have all the facilities apart from the games hall in use, so we are planning to run the activities in the first and last weeks of the holidays. The community use office has been moved into one of the huts in the rear car park area and we are continuing to operate from there."