The extra pressures of England's school rebuilding scheme are hampering the day-to-day running of some of the schools involved, a major report says.
The Building Schools for the Future scheme has been hit with delays
Head teachers felt constrained by a lack of time and support, an evaluation for the government of its Building Schools for the Future programme said.
And local authorities had to spend more on managing projects than they had originally thought, the report added.
But, it said, most teachers believed the scheme would improve education.
The government asked PricewaterhouseCoopers to undertake an evaluation of its £45bn school rebuilding scheme in 2006.
The team quizzed head teachers, local authority officials and stakeholders involved in projects in 25 schools during 2007 and produced its first report.
It begins with an acknowledgement that progress has been slower than anticipated, but asserts that head teachers believe the programme will result in educational improvements.
But a number of barriers to the whole BSF process were identified.
One of the key issues related to the extra pressures the projects put on school staff and their management teams.
"Overall, the findings suggest that additional resourcing required for BSF was having a significant impact on the day-to-day running of the school," the report said.
The issues centred on time, external support and financial constraints within schools and was also raised by local authority BSF managers and others involved in the projects.
Some 59% of head teachers surveyed said they did not have adequate support to release staff and 57% said they lacked adequate financial support to sustain the school.
Local council officials said there was a "shortage of time" to focus on BSF as a "long-term development opportunity".
This is an interesting response as ministers have explained away delays in the project with the need for those involved to take the time to get it right.
Most of the schools the report team visited did not have a dedicated BSF manager within their schools.
"Consequently, members of the senior leadership team had to free up additional time to attend meetings both internally and externally which added to their workload," it said.
Partnership for Schools, the body appointed by the government to oversee delivery of the programme, says schools should appoint senior staff to focus only on the project.
But some of those responding suggested this would be unworkable.
One of the head teachers described the bureaucracy and extra administration linked to BSF programme as "horrendous". Another bemoaned it as "unnecessarily" bureaucratic.
And there were also criticisms of the way schools were involved in the design of the future school.
The report suggested that consultation with staff and pupils was "insufficient and, to a degree, ineffective".
Schools minister Jim Knight said the report showed what very strong, positive expectations there were for this "once-in-a-generation opportunity to transform lives".
"We commissioned this official independent evaluation to listen to schools, to learn lessons and, where needed, to improve the management and delivery.
"There is no excuse for frontline staff to feel cut off from the design process and we have a duty to involve them at every stage so staff get the facilities they want and young people need."
PfS chief executive Tim Byles said: "As with any project of this scale, we are continually learning lessons and refining our processes.
"This first evaluation will help us in this, and we look forward to seeing the result of future research into the effectiveness of the BSF programme."
The three-year study will go on to measure its educational impact.