The NAO noted that: 'System-built buildings introduced in the post-war years can require disproportionate maintenance expenditure.'Essex, the largest education authority, was opening one school a week some 25 years ago. It now has 729 schools of all kinds and has found 138 timber-frame built schools in need of major repairs.It has done this in a rolling programme and how has only five schools left to repair.But this has extended the lives of these buildings by only 15 years, so the county has a relatively short time before it has to start on timber-frame refurbishment again, or else try to replace these buildings.It hopes to use the time in between to replace demountable buildings with permanent classrooms. Some secondary schools are managing with up to 13 demountable buildings which the council cannot afford to replace.A spokesman said: 'Our programme has involved stripping off cladding, replacing rotten timbers and installing upvc panels, but it only extends the life of these buildings by 15 years and then we will have to start again.'Sheffield, a council highlighted in the NAO report, has a Government allocation for school building work this year of £1.3 million, against £2.5 million last year, which was itself the lowest allocation it had ever received.Quite apart from the cost of maintaining its ageing traditional buildings, it has found serious deterioration in timber-frame schools and thinks 10 cannot be repaired in the long-term. It thinks £13 million is needed to replace these, and less serious repairs to timber frames will cost £1.1 million.According to the ACC, problems with more modern buildings date from similar Government penny-pinching at the time these were built. These false economies have stored up problems for the future.When a building deteriorates to the point that an emergency repair si needed, the cost is met usually at the expense of routine repair work elsewhere.Between 5 and 10 per cent of school maintenance budgets are spent on putting right damage caused by vandals an arsonists, according to the NAO. This in turn eats up money which could have been spent on repairs.The Government argues that since the number of school-age children is falling, councils could save money by closing schools which are no longer needed and moving pupils to other sites. It also says councils could spend money raised from selling surplus school sites on repairs.The councils retort that they cannot afford to close schools and transfer pupils as fast they would like, and that anyway the depressed state of the property market means there are few buyers for old schools. This leaves councils still responsible for meeting the cost of maintaining disused schools.However, it would be wrong to think that large numbers of school buildings are about to collapse on pupils' heads.The NAO found that only 75 accidents out of 7,252 in schools in 1989/90 resulted from poor maintenance.But it is undeniable that a major programme of repairs is needed.Parliament's public accounts committee will quiz top civil servants and ministers on the NAO report in the next few months.The Government can argue that councils can juggle money between different services to spend more on school buildings. But with its abandonment of the target to get buildings up to standard, the Government is set to take the bulk of the blame.