According to, existing buildings must comply with Sections 5, 6, 7, 8, 9 and 10, or 11 or Appendix G. Although, based on exception, historic buildings do not require to comply with these requirements.

Our building is an officially historic building in Portugal. Since the exception refers the US, can an historic building in Portugal be considered to this exception?

To which requirements this exception does apply? To Appendix G as well or only to the Sections mentioned before?

According to the historic building plans, the walls and floors have different (much larger than normal) widths. Should these widths be considered in the model (reducing the building floor area to the actual area)? Or should it be always considered (for any wall or floor) width equal to 0 (considering the building floor area measured with "external measurements"?