"Many schools that were promised by the NSW government as early as 2018 have remained in planning for more than four years without any substantial community updates or timelines provided," the report released on Wednesday said.

Poor demographic planning in response to the booming population growth in western Sydney has had a significant negative effect on a number of communities, it said, "leading to overcrowded schools (and) longer-than-acceptable commutes to the nearest school".

The NSW upper house committee found nine out of 10 of the most over-capacity schools are in greater western Sydney, with promised schools not built in suburbs such as Rydalmere, Marsden Park, Tallawong and Gregory Hills.

The report's 20 findings and 30 recommendations were informed by four public hearings since March and visits to numerous schools in northwest and southwest Sydney, as well as Gillieston Public School and Fern Bay Public School in the Hunter region.

Labor education spokeswoman Prue Car said the government neglect of western Sydney schools in particular was noticeable.

"The Perrottet government's mismanagement has left school communities across the state in frustration, with undelivered commitments and project planning delays which seemingly have no end.

"The legacy of this 12-year-old government on schools is delayed schools, demountables on playgrounds, and empty promises to families that continue to let the community down."

The committee linked this to pork barrelling, which was a persistent problem plaguing the Department of Education's priorities.

"A focus on delivering projects in government-held seats has been a factor in the delivery of school capital works," it said.

It recommended that School Infrastructure NSW publish benefit-cost ratios (BCR) for all school capital works projects exceeding $20 million and then rank the projects according to BCR value.

The report also found that parent representatives on project reference groups were required to sign non-disclosure agreements, making them unable to report back to their school. 

It recommended removing the gag orders as a first step towards transparency and that construction timelines for schools be published on the School Infrastructure NSW website.

AAP