Restoration. Any lawful nonconforming structure which has been involuntarily damaged by fire, explosion, flood, windstorm or similar cause to an extent of not more than 70% of its fair market value or which has been legally condemned may be restored within the limits of the existing foundation and within its original dimensions. Restoration shall commence within one year from the date of damage, destruction or condemnation and shall be carried on consistently, without major interruption, on a time schedule agreed to by the Zoning Officer at the time of building permit issuance. Where the extent of damage or destruction exceeds 70% of the fair market value, any restoration, reconstruction or new construction shall comply fully with the terms of this chapter.