Ringwood Junior School said the proposed single-storey structure would also provide an additional space for education during the day.
A planning application for the scheme has been submitted to New Forest District Council.
A planning statement written on behalf of the school by Ringwood-based EKL Design Ltd said it was important the school supported families through the provision of wrap-around care.
“The new building would be a single prefabricated structure,” the statement said.
“The building would consist of a multi-functional space that can be used to provide ancillary space for education during the school day, but importantly will provide a home for the ‘115 club’ who provide wrap-around care for pupils before and after the school day.”
Ringwood Junior School covers years three to six, with a three-form entry capacity.
Permission is sought to remove two existing timber cabins and erect a single-storey flat-roofed purpose-built space at the school site in Hightown Road.
The new building would have toilets and a kitchenette area.
The toilets have been described as an “important” feature to provide year six classes with their own facilities immediately adjacent to their classrooms.
EKL Design Ltd’s planning statement added: “The year six pupils are currently required to share toilets across the wider school complex with younger age groups, which is not desirable to the school, or readily efficient during lessons.
“The kitchen equipment will support the operation of the wrap-around childcare on site.
“The design is basic, functional, but entirely complimentary to the existing school complex and based on its location, will not detract from any of the aesthetics of the school.”
The timber cabins are described as “garden summer houses” that provide space ancillary to the principal educational activity at the school.
The application is currently being assessed by council planning officers, with a public consultation open until January 13.