The system for assessing design teams for new schools needs an overhaul to stop substandard buildings winning approval, the Government's advisers on architecture said this week.
Design quality counts for only a small part of the overall criteria by which teams of architects are judged by local authorities.
Councils give too much emphasis to how well a design team will work in a partnership with others rather than how likely it is to deliver a well-designed building, according to the Commission for Architecture and the Built Environment (Cabe).
The system needs a rethink if the amp;#163;45 billion Building Schools for the Future (BSF) programme is to deliver high-quality schools, the commission says. It has also called for a "design threshold" to stop poorly designed schools being built.
Its comments come as it was revealed that most of the BSF designs now seeking planning permission are substandard, according to experts.
Matt Bell, Cabe's director of campaigns and education, said: "Many of the schools coming through are not yet good enough."
Minimum standards and changes to the procurement process would "send a very clear signal to bidders that good design is a core requirement, not an optional extra".
A Freedom of Information request by The Guardian discovered that 21 of the 24 school designs that were seeking planning permission or had appointed a design team were either "not yet good enough" or "mediocre", according to design panels run by Cabe.
The news follows a series of setbacks and delays for the school building programme, which aims to rebuild or refurbish every secondary in England by 2020.
Jim Knight, the schools minister, said: "We don't build mediocre schools. The fact is that most of these designs are at initial planning stage, and they are all improving massively as they advance through the planning process."
A spokeswoman from the Department for Children, Schools and Families said no final decision had yet been taken on introducing a design quality threshold.
But Mr Bell predicted that the credit crunch, which is slowing the construction industry, could benefit BSF. Firms are likely to employ better architects because of the significant amounts of money the programme will provide, he said. Design quality would also improve as headteachers became more demanding about what they wanted from new schools.
Ty Goddard, director of the British Council for School Environments, said fundamental changes were needed to the whole procurement process to include the views of teachers and pupils. The current "tinkering and fiddling" is not sufficient, he said.