Primary schools in Kirklees are struggling to find places for pupils as the population grows.
Schools in Cleckheaton and Dewsbury West have been forced to expand or take in more pupils in order to meet demand, council papers show.
There has been a rise of almost 20 per cent in the number of reception-aged children since 2000 – from 5,000 to nearly 6,000.
Key Stage One classes have a 30 place class size limit.
A report to Kirklees Cabinet states that inner urban areas show some significant pockets of population growth.
“This demand is placing significant pressure on primary school places which can only just be met,” it adds.
Birth rates, immigration into the UK and new housing developments are factors affecting demand.
However, recent figures show that nearly 97 per cent of Kirklees families received one of their three preferences for the September reception intake.
The council has formulated five year plan to tackle the issue.
In 2013, Boothroyd Junior and Infant School, Dewsbury, was permanently expanded in order to continue to provide 30 additional pupil places.
Heaton Avenue Primary School in Cleckheaton has admitted children above the Published Admission Number (PAN) for the past two years.
PAN is the maximum number of pupils intended to be admitted to the relevant year group in a given school.