Section 81Z. A city or town in which the subdivision control law is in effect shall, by ordinance or by-law, provide for a board of appeals, which shall have jurisdiction to issue a permit for the erection of a building under section eighty-one Y. Such board of appeals may be the existing board of appeals under the local building or zoning ordinance or by-law; provided, that if the board of appeals under the local zoning ordinance or by-law in any city or town is also the planning board in such city or town, it shall not act as a board of appeals under the subdivision control law. The mayor or selectmen shall appoint the members of the board of appeals within three months of the adoption of the ordinance or by-law. Pending appointment of the members of the board of appeals the city council or selectmen shall act as a board of appeals. Any board of appeals newly established hereunder shall consist of at least three members, who shall be appointed in a city by the mayor subject to the confirmation of the city council, or in a town by the selectmen, for terms of such length and so arranged that the term of one member shall expire each year; and said board shall elect annually a chairman from its own members and a clerk. Any board so newly established may also act as a board of appeals under the local building or zoning ordinance or by-law, or under both.
Any member of such a board of appeals may be removed for cause by the appointing authority upon written charges and after a public hearing. Vacancies shall be filled for unexpired terms in the same manner as in the case of original appointments. Ordinances or by-laws adopted hereunder may provide for the appointment in like manner of associate members of the board of appeals; and the chairman of the board may designate any such associate member to sit on the board in case of the absence, inability to act or interest on the part of a member thereof, or in the event of a vacancy on said board may designate any such associate member to sit as a member of the board until said vacancy is filled in the manner provided in this section.