Nothing in this chapter shall prevent the restoration, within one year, of a nonconforming structure destroyed or damaged by fire, explosion, act of God or the act of the public enemy to an extent of not more than 50% of its reconstruction cost at the time of such destruction or shall prevent the continuance of the use of such building, or part thereof, provided that such restoration does not violate the provisions of this chapter to any greater extent or in any other way than at the time of such destruction. Any structure destroyed in the manner aforesaid, to an extent exceeding 50% of its reconstruction cost at the time of such destruction, may be reconstructed and thereafter used only in such manner as to comply with the provisions of this chapter. In the discretion of the Building Inspector, said one-year period may be extended up to, but not exceeding, one additional year, so long as due diligence is being pursued by the owner. Any further extension shall require the approval of the Board of Trustees. In any such application to the Board of Trustees, in determining whether or not to grant said extension, and the period of time for which such extension should be granted, the Board of Trustees may consider the same criteria and impose the same conditions as it would for an extension of a building permit.