No order of the Board of Zoning Appeals permitting the erection of a building shall be valid for a period longer than one year, unless a building permit for such erection or alteration is obtained within such period and such erection or alteration is started and proceeds to completion in accordance with terms of such permit.
No order of the Board permitting a use of a building or premises shall be valid for a period longer than one year unless such use is established within such period, provided, however, that where such use permitted is dependent upon the erection or alteration of a building, such order shall continue in force and effect if a building permit for said erection or alteration is obtained within such period and such erection or alteration is started and proceeds to completion in accordance with the terms of such permit.
(1975 Code § 5.188)