It could take up to 20 years to make all schools in Scotland fit for purpose despite billions of pounds of recent investment, a report says.
Audit Scotland said that since 2000 £3.9bn had been committed to new schools and improvements.
That is expected to rise to £5.2bn by April. About a third of schools were said to be in poor or bad condition.
The Scottish Government said schools had been neglected for decades. Labour accused the SNP of a lack of action.
In the late 1990s, the then Scottish Executive began a programme of school building and renewal.
According to the report, published jointly by the Accounts Commission and the auditor general, it included the promise of financial support for councils which used private finance (PFI) and public private partnership (PPP) to renew their schools.
A new strategy in 2003 aimed to raise the quality of the school estate over a period of at least 10-15 years.
John Baillie, chairman of the Accounts Commission, said: "Ten years ago many of Scotland's schools were in a state of serious disrepair.
"Since then, 219 new schools have been built and many others refurbished. Councils are working hard to improve how they manage their school estates."
Local-government body Cosla said the progress demonstrated the "commitment" councils had towards improvement "despite resource constraints."
But the report argued that the national strategy lacked "clear and consistent definitions" for refurbishment, renewal or improvement .
It said it was not possible to measure exactly how many schools across Scotland had been improved.
Robert Black, auditor general for Scotland, said: "The national strategy should be reviewed, using the better information that is now available to specify the performance targets."
Minister for Schools Maureen Watt told BBC Radio's Good Morning Scotland programme: "We've inherited a problem of decades of under-investment, it's not a problem that's going to be solved overnight."
Ms Watt said the government was in the process of developing an alternative funding mechanism, the Scottish Futures Trust, to replace the previous executive's PPP building programme.
She added: "We know that parents and pupils want new schools, it was prudent for us to allow those projects to go ahead, but in terms of building from now on, we are going to look at more prudent methods of building so that it won't mortgage our children's future."
The minister also claimed that local authorities had been given funds to continue school building commissioning and that the Scottish Futures Trust would finance school building when it comes in.
Ms Watt said 100 inherited projects were going ahead and that 200 more would be set in place in the lifetime of the parliament.
Labour said the report highlighted the work of the previous executive in improving schools.
Its education spokeswoman, Rhona Brankin said: "The SNP are trying to hide behind their plans for a Scottish Futures Trust, but their ongoing consultation is causing nothing but unnecessary delays and cancellations of pending projects."
The Conservatives argued that there needed to be greater clarity about what a Scottish Government and council review would actually entail.
The Liberal Democrats urged the government to implement the recommendations and publish a clear timescale and funding details.
The report also highlighted issues of design. In a sample study of 18 new or refurbished schools, although pupils and staff were generally satisfied, they said the design could be better.
Many said their schools overheat and have poor ventilation.
The report said an early problem was that environmental sustainability was not a key factor in the designs, but more recently there had been some examples of environmental factors being considered.