Any existing one- and two-family dwelling may be extended, altered, changed, or rebuilt, provided that said alteration or reconstruction is performed within the existing footprint. The existing footprint shall be defined as the perimeter outline of the structure, excluding eaves, decks, and porches. Any legally existing non-conforming eaves, decks, and porches may be reconstructed in their former entity only. No expansion of living space into said deck(s) or porch(s) is permitted without a Special Permit from the Zoning Board of Appeals. No exemption in height is permitted outside the prescribed setbacks without a Special Permit from the Zoning Board of Appeals. However, height extensions relating to flood proofing pursuant to 780 CMR and F.E.M.A. regulations within the prescribed height limit are permitted as a matter of right.