Urban infill in Perth's inner suburbs is placing increasing pressure on public schools, and parents are concerned that green space is being sacrificed for extra classrooms.

Earlier this year parents at Bassendean Primary School in Perth's east held a sit-in in a last-ditch attempt to stop part of the school oval being turned into a car park.

The two high schools in the western suburbs, Shenton College and Churchlands, are bursting at the seams and playing fields are now used to accommodate students in demountable classrooms.

The latest school to come under pressure is Inglewood Primary School, where the Education Department has announced plans to use a portion of the school oval for a two-storey building.

Parents have expressed concern about the loss of green space at the school and said they had not been consulted on the proposal.

"It was a bit of a shock for me, and my first thought is where is my son going to be playing?" Petra, whose son attends the school, told 720 ABC Perth.

"We just had a building added five years ago to accommodate more children and now another five years later we are going to do another building."

"[The oval] is the only piece of open space."

Inner-city infill adds to student numbers

John Fischer, executive director of infrastructure at the Education Department, said urban infill in the inner-city suburbs had placed space pressure on many schools.

"Inglewood, over the next 10 years, will have an extra 100 to 150 students," he told 720 ABC Perth.

The normal way of dealing with extra students is to put in transportable classrooms but "that is very space consuming on the site", he added.

"With Inglewood we did look at the options, including redeveloping the existing buildings or optimise the space."

The department concluded the new double-storey building was the best option.

"It's really a trade-off between having the right facilities versus some green space," Mr Fischer said.

Sandpit roster for primary children

But Petra said she was concerned that the decision had been rushed and that children already had insufficient outdoor play space.

"At the moment the kids are on a roster and my son is allowed to play only two days a week in the sandpit."

"If we need the building, that is welcome, but we have to find a better solution."

Mr Fischer predicted high-rise options would become more common for schools needing space in the future.

"I think we will see a range of schools in the future," he said.

"Certainly those closer to the city will be under pressure to be more high rise."