A proposed expansion plan costing more than £2 million would make a St Albans primary school the biggest in the city.
Hertfordshire County Council plans to expand Garden Fields JMI School in Townsend Drive to take another 30 reception children from September 2015 and in each subsequent year thereafter, making it a three form entry school.
Reception places would grow from 60 to 90, which could mean the current capacity of 420 pupils would increase to 630, excluding nursery children.
The £2.7 million proposal has been drawn up in response to a projected shortfall of primary places in schools in other parts of the city.
Garden Fields has been chosen because "it is located close to the area of demand and the site is capable of accommodating an enlargement".
The county council says it is not possible to permanently expand other schools in the area. These are Abbey C of E Voluntary Aided School, Aboyne Lodge, Alban City School, Fleetville Infant School, Killigrew Primary School, Mandeville Primary, Maple Primary School, Oakwood Primary, Prae Wood Primary, Samuel Ryder Academy, St Adrians Primary, St Alban & St Stephen Infant and Nursery, St Alban & St Stephen Junior, St Michael’s Primary and St Peter’s School.
There are currently 487 permanent reception places available in areas serving those schools.
The council predicts there will be a demand for 535 places by 2017/18. However, figures show there will be a shortfall of 48 places by then.
Additional accommodation and play space would have to be provided at Garden Fields to meet demands.
The proposal may also involve the relocation of St Albans Music School, which is on the same site. It has recently expressed support for the move and negotiations are currently underway to find alternative premises.
Garden Fields headteacher Mr Chris Jukes said it was important "the views of the school were represented".
He said: "From a governor’s point of view, it is very important to keep the communication channels open between us and our parents, so they are properly informed with the facts when they make their comments within the consultation.
"From the school’s point of view, we would want to ensure, if these plans go ahead, we end up with the space that is required, the correct resources and adequate facilities for a three form entry school.
"Ourselves, the local authority and music school have been working with each other to ensure there are adequate school places for children in St Albans.
"This has got to be the correct solution to meet the needs for a three form entry school."
County councillor Chris Hayward said: "We aim to commission the right number of school places for children and young people in the right locations to ensure local children can continue to attend a school in a community close to where they live."
A consultation exercise is underway with those who may be affected by the expansion and this will close on March 12.
To submit a comment visit: https://www.hertsdirect.org/websurveys/cgi-bin/qwebcorporate.cgi?CVAU4N.