BRUNSWICK, Maine — Bowdoin College’s plan to build a three-story administrative office on Maine Street received unanimous approval from the Brunswick Planning Board on Tuesday.

Board approval of Bowdoin’s final application was required before the college could replace an existing building at 216 Maine St. with an office that has a nearly 3,500-square-foot footprint.

Construction of the Federalist-style office, which will follow demolition of the old building, is expected to begin in April and conclude in November.

The office will provide space for about 30 employees from Bowdoin’s human resources, controller and financial aid departments. The latter two departments were previously in the former McLellan Building at 85 Union St., home of Brunswick new town office, which will continue to have college offices on its third floor.

Responding to a previously aired concern about the building’s size, lead architect Berton Bremer showed a diagram that juxtaposed the 40-foot tall building with the adjacent Joshua L. Chamberlain Museum, which stands at 36 feet, and The Inn at Brunswick Station, which stands 48 feet on the opposite side.

Bremer said his firm, Cambridge Seven Associates, also determined the building would not cast any significant shadows on surrounding buildings.

Staff parking for 39 vehicles will be in the parking lot for the new town office, made available as part of a January 2009 agreement with the town. The new building will have three of its own parking spaces for deliveries and visitors, including one space accessible for people with disabilities.

S. Catherine Longley, Bowdoin’s treasurer and senior vice president for finance and administration, said faculty, staff and visitors will also have 13 parking spaces at the college’s Howell House at 228 Maine St..

She said the Maine Street parking will be available to the public starting in September for nearby amenities, including Maine State Music Theatre, First Parish Church and access to downtown.

In late February, Bowdoin received final approval to convert a two-story, 9,000-square-foot former retirement home at 52 Harpswell Road into a 65-student, chemical-free residence hall that will be open by August.