Chilmark voters will meet Saturday to take up the question of whether to approve another $1.2 million to advance the construction of a new firehouse and Tri-Town Ambulance building.

The meeting begins at 1 p.m. at the Chilmark Community Center. There is one article on the warrant.

The new fire and ambulance complex is planned at 339 Middle Road, featuring two buildings in a campus-style layout. On the drawing board since 2014, the project easily passed town meeting last year with an $11 million budget. Now with rising construction costs a factor, the town is asking voters to approve an additional $1.2 million in order to break ground.

Town administrator Tim Carroll said bids for the project came in higher than expected.

“Higher than we estimated originally and even higher than we estimated in December,” he said. “The availability of construction materials is a very tight market right now.”

Under a strict deadline to contract with a builder for the project, the town is unable to push the question to the annual town meeting next month, Mr. Carroll said. And full funding for the project must be approved before a contract is signed. If the article passes Saturday, he said the town plans to sign a contract with Dellbrook of East Falmouth for the $12 million project on Monday and begin demolition at the site immediately.

Mr. Carroll said the expected time frame for the project is 18 months. If voters fail to approve the added spending, he said selectmen would have to weigh reducing the scope of the project, or delay it.

He emphasized that $1.2 million question is the last hurdle the town faces before work on can begin.

“We’re slowly coming to fruition,” Mr. Carroll said.