Sydney's top independent schools are outspending public schools by three to one as they invest in libraries, lecture theatres and gyms in a multimillion-dollar ''arms race'' to attract lucrative enrolments.
Some elite independent schools are spending more than $30 million in capital works to pull in students.
Newington College in Stanmore spent $78 million on capital works between 2009 and 2012 - more than any other school in NSW.
Knox Grammar was the second-biggest spender with $62.7 million over the same period, ahead of Cranbrook School on $57.6 million and Sydney Church of England Grammar School (Shore) on $51 million, according to the My School website.
Newington spent $33.7 million on infrastructure in 2012.
Cabramatta High School - whose upgrade included the construction of four new teaching blocks - was the top-spending public school, with $27.79 million spent on capital works from 2009 to 2012.
Helen Proctor, a senior lecturer in the faculty of education and social work at the University of Sydney, said elite private schools were engaged in an ''arms race'' for the most impressive theatres, aquatic centres and sport stadiums.
''In that high end of the market, it's very important for their image to have the best and the brightest of everything,'' she said.
In 2012, NSW independent schools spent $2395 per student on capital works, with Catholic schools spending $1074 and public schools $747, according to the latest figures from the federal website.
Infrastructure spending has been in steep decline in all school sectors since the first Rudd government's Building the Education Revolution program peaked in 2010. That year, public spending per student was $4058, with the independent schools spending $4885. Catholic schools spent $3535 per student.
Illustrating the amount of money some schools spend on building projects, the Master Builders Association of NSW's Excellence in Construction Awards has four categories for private schools: up to $5 million, $5 million to $10 million, $10 million to $20 million and $20 million and over.
The Newington College development claimed the honour for the top bracket last year for a new $20 million building that includes a library, lecture theatre and cafeteria. The project was funded by donations and parent fees.
The top category for public schools - over $5 million - went to a project to rebuild the Clarke Road School in Hornsby for students with physical and mental disabilities.
Public, Catholic and independent schools are calling for major increases in government capital funding to cope with the 600,000 extra students expected to be enrolled by 2020.
The disparity in capital works spending between NSW public and independent schools is larger than the national average.
Angelo Gavrielatos, national president of the Australian Education Union - which commissioned the capital works spending research - said the gap between schools would stop students reaching their potential.
''Increasing capital funding to schools which already charge fees and have their own resources has simply reduced equity in the system,'' he said.
NSW public schools received an average $679 in government funding per student in 2012, compared with $338 for Catholic schools and $379 for independent schools.
Barry Wallett, deputy executive director of the Independent Schools Council of Australia, said elite private schools comprise only a small proportion of the independent sector. They receive little to no government funding for capital works.
Mr Wallett said most independent schools are at capacity and are spending more to cater for growing enrolments.
Demand is especially strong for low-fee independent schools in areas such as south-western Sydney, according to the Independent Schools Association of NSW.
National Catholic Education Commission executive director Ross Fox said Catholic schools face growing demand but receive the least government funding per student.
''Catholic education across Australia is facing significant challenges to build new schools and expand existing ones to accommodate the growing student population,'' he said.