The Montgomery County school system plans to rethink its list of which schools are next in line for modernization, after a report that strongly criticized the way those decisions are made.

The ranking system is based on outdated information, marred by factual errors and favors total reconstruction over renovation, according to the July report by the county’s Office of Legislative Oversight, the research arm of the County Council.

Until the report’s release, the school system had intended to keep its list unchanged until at least 2031. But the oversight office found that other large school systems, including Baltimore County, Fairfax County and Dallas, regularly revisit and adjust their construction priorities.

“It’s definitely disturbing,” said council member Tom Hucker (D-Silver Spring). “This doesn’t inspire public confidence.”

In a July 22 letter to oversight office director Chris Cihlar, interim Superintendent Larry A. Bowers said the school system will examine the ranking issue with an eye toward incorporating changes into its updated capital improvement program, which will be released in October.

“These are important findings for MCPS to consider,” Bowers said.

The school system will spend about $117 million annually for the next five years on its revitalization and expansion program, completing two to three projects every 12 to 18 months. It works from a list of schools — mostly built before the mid-1980s — that were scored based on the condition of electrical and plumbing systems, fire protection, exterior walls, energy efficiency and other factors. The higher the score, the closer a school was to the front of the queue.

But the order of the list hasn’t changed since it was drafted in 2011, the oversight office found. That means the rankings don’t account for recent deterioration in buildings or for smaller, incremental improvements by the school system that might reduce the need for renovation or expansion.

For example, a few months after Fox Chapel Elementary in Germantown was ranked 21st on the list, the school system installed new fire sprinklers and strobe lights, the report said. Had that safety upgrade been taken into account, the school’s overall score would have been 10 points lower, boosting six other schools ahead of it in line.

“We’ve been telling the county this for a long time. Those scores need to be revamped. What was true in 2011 is not necessarily true today,” said Laura Stewart, president of the parent-teacher association at Woodlin Elementary in Silver Spring, which is 25th on the list — at least 10 years from getting started.

Stewart said Woodlin’s 1940s-vintage building, last renovated in the 1970s, “is way overdue for a complete overhaul” of its cramped cafeteria and gymnasium.

The school is projected to be 136 percent over capacity for the coming school year. But overcrowding is not among the factors weighed in construction and renovation decisions — a policy that the oversight office questioned in its report.

School officials said that once a school is at the top of the line for renovation, capacity issues are taken into account. Over the past five years, 17 of 19 completed modernization projects have added 180 classrooms and more than 4,000 seats for students, school officials said.

The priority list from 2011 is also skewed by errors made by an outside consultant, the report said. For example, Piney Branch Elementary in Takoma Park is 15th in the queue, boosted in part by high energy and water-consumption costs. But it is also the only elementary school in the county with a swimming pool — a fact that the consultant did not take into account.

Incorrect square footage was used to calculate rankings for at least six other elementary schools, the report said.

The Montgomery report also questioned the county’s reliance on complete or near-complete reconstruction of aging schools, rather than renovation.

School system officials said reconstruction to meet current-day specifications often costs less than renovating older buildings. Many schools constructed in the 1960s and 1970s were of poor quality and pose challenges to renovation, Bowers’s letter said. Low ceilings, for example, make it impossible to install modern duct work. Bowers also said it was “nearly impossible” to add new floors to buildings because of poor construction.

But the oversight office noted that some other school systems take a different approach. Fairfax County, for example, cites environmental concerns as a reason to prioritize renovation over reconstruction.

Officials in Fairfax calculate that it takes 45 years for the initial carbon contribution of an elementary school to be absorbed. Fairfax also says that school renovations produce less non-recyclable demolition debris than full reconstructions do.

School modernization has been a subject of controversy in the District as well. Mayor Muriel E. Bowser (D) pushed back the schedule for dozens of projects in her proposed six-year, $1.3 billion school construction plan because of cost overruns and a slowdown in capital spending.

A recent audit found other lapses in financial management, accountability and transparency in the District’s renovation program.