Fulton County commissioners signed off Wednesday on a proposal to spend at least $150 million to overhaul and expand what is already Georgia's largest local library system.

The board did not set how or when they would ask voters to pay for it, though library officials have suggested a countywide vote on a bond in November.

Preliminary numbers show the plan would add eight libraries at a cost of nearly $86 million. Fulton would ask residents to pay another $64 million to renovate or add on to existing branches.

Officials stressed those numbers could change substantially by next month when commissioners are supposed to decide on whether to ask for a bond issue.

The estimates don't include land costs, increases for construction costs over time or contingency costs officials plan to add to each project.

Five small libraries would be closed in southeast and west Atlanta and replaced with larger facilities.

Commissioners supported it 5-0-1, with Robb Pitts abstaining.

"I'm impressed with the report and the plan from end to end," said Commissioner Nancy Boxill.

Pitts abstained after making an impassioned plea to his colleagues to delay the vote until April. He wanted more time to research whether Fulton should accept an offer from developer Ben Carter to buy the Buckhead branch, demolish it and include the property in his redevelopment plan for Buckhead Village.

The board's vote essentially rejected Carter's plan because his offer was not part of the plan approved Wednesday. The unique branch with its unusual contemporary design has had critics and supporters since it opened nearly 20 years ago.

On Wednesday, several supporters of the design pushed commissioners to spare the building.

"The price offered can't give you what you already have," said Sally Combs of Atlanta. "My vision is to expand the building using the original architects."

David Green, a professor of architecture at Georgia Tech, agreed the building should be preserved. "It remains among a handful of buildings that put Atlanta on the map for modern architecture," he said.

The program presented Wednesday started with a consultants' study in 2006 and continued last year with a series of 37 meetings throughout Fulton.

In the end, the plan calls for new branches in Alpharetta, Milton, northwest Atlanta's Riverside area, near Wolf Creek park in south Fulton and the Stewart Avenue-Lakewood area in south Atlanta.

Other new, smaller branches would be built in Chattahoochee Hill Country, East Roswell and southeast Atlanta.

Fulton would close or end leases at Bankhead Courts, Bowen Homes, Carver Homes, Georgia Hill, Perry Homes and Thomasville Heights.

Even without the building program, Fulton has 34 branches and a yearly budget of more than $30 million. Still, the system often fares poorly in national ratings when compared with Seattle, Cleveland and other major urban cities.