"At least 1,000 parents have visited our school seeking Form One slots, but we have turned them away because we don't have adequate facilities," Onsare said.
He said the ministry had allocated the school 337 Form One slots.
He said facilities at the school, which has a population of over 2,000 students, were overstretched.
"We require at least four additional classrooms, two more dormitories," he said. The four laboratories are inadequate, he added.
He disclosed that four classrooms put up for the CBC programme would be used to accommodate the growing number of students.
A spot check by The Standard revealed that most schools have inadequate facilities even as the government advocates 100 per cent transition to secondary school.
At Goseta Boys, the principal said they had set aside four classrooms for Form Ones.
The principal John Murumba said they would make use of the two classrooms that had been built for junior secondary and another two put up by CDF and parents.
"We have no problem with classrooms. We thank the local CDF and our parents for their support towards improving facilities," said Murumba.
St Joseph Girls, St Marks Cherangany, St Francis Makunga and Anderson Mixed have also witnessed a big number of parents seeking vacancies.
St Joseph Girls principal Rosebella Orwaru said the demand for Form One slots was overwhelming.