Marietta City Schools plans to cut its budget 4 percent through belt-tightening measures that include outsourcing 22 custodial positions. There are no furlough days or teacher layoffs planned.

Superintendent Emily Lembeck said that could change if the system doesn’t receive the funds expected from state and federal sources. Last year’s budget was based on a revenue shortfall of $5.9 million.

The district’s Board of Education will vote on the 2012 budget at 7 p.m. Tuesday at the school headquarters at 250 Howard St. A public comment hearing will be held a half hour before the meeting. The $74.5 million budget is $3.1 million less than last year’s.

The proposed budget for the fiscal year starting July 1 will eliminate a food service warehouse position, consolidate two bus routes and use $3.4 million in reserves. Two alternative and special education facilities will be combined at one location. The city system has 11 schools and 8,000 students.

School officials said the budget process has been challenging since 2008. Lembeck said privatizing custodial jobs was a difficult decision based on the economy, which has driven school systems to look at business and staffing practices.

“It becomes more difficult to protect what happens in the classroom without looking at some services that are not directly related,” Lembeck said. “Reducing days of instruction through furloughs and larger class sizes is not in the best interest of our core business of educating students.”

Marietta City Schools started outsourcing custodial jobs seven years ago through attrition. Schools spokesman Thomas Algarin said increasing the privatization will save the district $223,242 a year. Thirteen head custodians will continue as school employees and those left will have to apply to ICS Contract Services in Atlanta for custodial work after June 30.

Many other school systems have outsourced jobs to save money. Joe Edgens, executive director of facilities for the Nashville Public Schools System, said his district privatized about 618 custodial and 44 ground services positions in 2010, saving the system $5 million to $6 million a year. Nashville has 78,000 students and a proposed 2012 budget of $670 million.