8. Any person shall be presumed to be a contractor who:(1) offers for sale or exchange a building or a civil engineering structure, unless he is able to demonstrate that the construction work of such building or structure was not carried out for the purpose of sale or exchange; or
(2) undertakes new construction work less than two years after the date a municipality issued the building permit for previous work or, if no such permit was issued, after the start date of the earlier work.