The clock tower in Carterton is yet to be ruled out as an earthquake risk in an ongoing appraisal of council buildings in the town.
Milan Hautler, Carterton District Council planning and regulatory manager, said original plans for the clock tower are missing and would be "extremely valuable" to aseismic assessment of the structure to determine the type and quality of its reinforcing.
He said "there are strong suspicions" the blueprints are in the Ministry of Works' archive in Wellington.
The clock tower was built in 1962 and features the original clock and bells from 1907 when they were housed in the post office, which was severely damaged in an earthquake in 1942.
Mr Hautler said any strengthening work the tower may need will be established before demolition would be considered.
The council had assessed its inventory of buildings including the tower in High St, the Memorial Square toilets, and in Holloway St the council offices, a former factory, events centre, council yards, and the former courthouse.
Engineers scrutinised the buildings last year and the toilets were demolished and restrengthening work proposed for the council offices.
Last year, the Times-Age reported 94 buildings had been identified as potentially earthquake-prone in Carterton district, six require remedial work, two have been demolished and 62 still needed to be assessed.
