Franklin County commissioners voted unanimously Tuesday to study a proposed regional jail put forth by sheriffs in three western Maine counties.

Under the proposal, Franklin County would join with Oxford and Androscoggin counties in building a regional correctional facility that could house about 500 inmates.

The three sheriffs — Scott Nichols in Franklin County, Eric Samson in Androscoggin and Christopher Wainwright in Oxford — unveiled the proposal earlier this month in a joint letter to the three county governments. They say the county jails face overcrowding and rising costs, and that a regional jail could save money and improve programming.

Franklin County commissioners on Tuesday voted in favor of hiring a consultant to study the proposal in a joint project with the two other counties.

Androscoggin County officials are scheduled to take up the matter on Nov. 19. Oxford County commissioners had the issue on their agenda for Tuesday, but commissioners voted to table the measure in order to seek more information.

The three sheriffs held joint meetings recently with county administrators Amy Bernard of Franklin County, Jeff Chute of Androscoggin and Zane Loper of Oxford to consider the proposal.

Androscoggin County pays $700,000 or more each year to board inmates at other facilities because there is no room at the county jail in Auburn. The jail has a capacity of 160 inmates, but officials say the facility exceeds that on a daily basis.

Franklin County, with a 39-bed capacity, has been overcrowded since this past summer. It pays $100 a day to board inmates at the Somerset County Jail in Madison.

On Tuesday, Nichols said, they had 39 people in custody but still needed to board four people in Somerset County to make room for any new inmates.

Oxford County, with a capacity of 47, also has to board inmates at other jails and pays $95 a day or more per inmate depending on the facility. In early October, on a couple occasions that amount totaled about $3,000 a day.

All three existing jail buildings are many decades old: Oxford County opened in 1979; Franklin County around 1982; and Androscoggin County around 1991.

There are about 100 corrections officers between the three facilities, Nichols said, with about 50 in Androscoggin County, 30 in Oxford County and 20 in Franklin County.

The majority of the cost to operate a correctional facility is staffing, Nichols said, and by having one jail the three counties may be able to reduce personnel expenses as a whole, he said. A unified medical staff could also be established as well to provide a better system for medical treatment for inmates, he said.

There are also challenges to a regional jail, including funding, unifying policies and a regional data collection system that aligns practices.

A regional facility could not be in Auburn, Farmington or Paris, where the current jails are located, Nichols said. It would need to be in a central location that is accessible for all three counties.

Nichols said they would probably be able to seek federal money for a modern correctional facility, which are now being built in premanufactured pods. Franklin County Sheriff’s Sgt. Ryan Close said they are now able to build jails in a third of the time it used to.

Nichols said a new facility could factor in growth and possibly board inmates for other jails and bring in money to help support the system.

Franklin County Commission Chairman Bob Carlton of Freeman Township said he and the sheriff had talked about this before. “What we are seeing around the state is more collaboration and it’s got to happen,” Carlton said.

The Maine County Commissioners Association will tour the Two Bridges Regional Jail in Wiscasset, which is a collaboration between Sagadahoc and Lincoln counties.

Like Two Bridges, any new facility for the three counties would be a separate entity and funded by all three counties. It would have a board of overseers and with members from each county commission.