The demolition of the buildings on the former Oakdale Comprehensive School site has cost Caerphilly County Borough Council more than £750,000.
The council has revealed that the cost to demolish eight Oakdale school buildings was £776,777.
This is well within the original estimate of £1.021 million.
A spokesman for the council said: “The works required the removal of a significant amount of asbestos by specialist contractors and the scheme was completed last year.”
The cost included the necessary invasive pre-demolition asbestos survey.
The cost of the demolition was funded by reserves set aside by the council.
Oakdale school closed at the end of June 2017 along with Pontllanfraith Comprehensive School.
The schools merged following the completion of the new Islwyn High School.
Last year plans to demolish Pontllanfraith school were put on hold until the end of March so the council could consider the future of the leisure centre.
According to the award notice on the Sell2Wales website for the demolition of Oakdale school contract, the plans to demolish Pontllanfraith school have been delayed further.
The contract says: “Bidders shall note that the tender process for lot two demolition of Pontllanfraith Comprehensive School has now been cancelled and therefore no contract was awarded for this package of work.”
Both sites have been earmarked by the council for housing.