tmurray
SAWHORSE
But once you are invited in, I do not believe that is an illegal search.
As an example, police will regularly ask for permission to search a car/house/backpack/etc.. If one says no, then a warrant is required; if one grants permission and something is found, it would be admissible and would not be constituted as an illegal search.
Only if the owner gives you explicit permission to search the entire building.
The courts will ask if it is reasonable to assume that you have the owner's permission to search their entire house without their expressed permission. When a building permit is completed, an administrative search is naturally required to verify compliance with all the various codes and legislation. That person is essentially giving us prior authorization to search that portion of the building that is impacted by the construction and that portion only.