Montauk voters overwhelmingly approved a $7.5 million renovation and expansion of the Montauk Library on Tuesday, voting 245 to 81 in favor of the library’s bond proposition. The project will add 5,000 square feet of space to the 9,000-square-foot building, most of that by filling in double-height areas in the existing library. A 1,600-square-foot addition will house a new entry area and exhibit and gallery space that the library is referring to as a local history and fishermen’s center. The project will also triple the children’s space in the library and provide a new enclosed teen room. Adult space will be reconfigured, and second-floor terraces will be added above the entryway addition and on the ocean-view side of the building.Because the library district follows the school district boundaries, voting took place at the same time as school district budget votes and board elections. The New York State Education Department must sign off on the plans. The library expects to put the project out to bid in the fall and hopes to begin construction this winter. It is eyeing a fall 2020 completion date. The library was built at its current spot in 1991.