The Prime Minister pledged £ 1 billion in funding for 50 major school building projects in England.
There will also be an additional £ 560m for repairs to dilapidated school buildings.
“It is important to lay the groundwork for a country where everyone has the opportunity to succeed,” said Boris Johnson.
But principals said the National Audit Office had identified a £ 6.7 billion needed repair portfolio in England’s 21,000 schools.
A program of reconstruction, renovation and repairs is being launched by the prime minister on Monday.
It will address the problems of aging, ruined school buildings and also the need to create extra spaces to increase the number of high school students.
The 50 school construction projects, which will be identified at the end of the year, will begin in September 2021, in a 10-year program with a £ 1 billion funding.
There will be an additional £ 560m for school improvements and repairs for the next academic year – and £ 200m for improving higher education colleges, previously announced.
“This important new investment will ensure that our schools and colleges are fit for the future, with better facilities and new buildings,” said Johnson.
Geoff Barton, leader of the ASCL teachers’ union, took a “significant step in the right direction” – but said that “many children are studying in buildings that are not fit for purpose”.
He warned that repairs were “desperately needed and long overdue” – and highlighted the concerns raised three years ago by the public spending watchdog, the National Audit Office -, saying the problems have “worsened” since then.
In a 2017 report, NAO warned of the deterioration of school buildings – and said it would cost £ 6.7 billion to bring buildings to a “satisfactory” level and another £ 7.1 billion to bring them up. for a “good condition”.
He reported that many school buildings were “near the end of their useful lives” – and that major defects were likely to increase.
Following the 2017 NAO warning, the government announced £ 2.4 billion for school repairs and extra places.
Paul Whiteman, of the National Association of Principal Teachers, supported the extra funding after a “decade of underinvestment” and warned that the school’s funding “should never be allowed to fall into such a dangerous state again”.
Layla Moran, a spokesman for education for the Liberal Democrats, said the promises were “to turn on substance” and that schools needed “urgent investment” rather than “vague numbers drawn out of thin air”.
The Department of Education says funding for building improvement is part of a broader investment in schools – including £ 650m for coronavirus recovery funding and £ 350m for tutoring.
There was also a commitment to increase school spending by £ 7.1 billion by 2022-23 – which the Institute for Tax Studies says will reverse previous cuts in school budgets.
Education Secretary Gavin Williamson said: “Replacing and upgrading poorly maintained school and college buildings with modern, energy-efficient projects will provide our students and teachers the environment they deserve and support them to maximize your potential “.