He really may not know the address. If it's a complete new build, it may not have been assigned a physical address yet. If it's an already established building being remodeled, there would have been an address already assigned to it, but that doesn't mean he remembers what it is, but he can get it.
If it's in a state of construction, visitors may not be allowed on site due to insurance regulations in case of accident or injury.
Or it could have signs or indications of the other companies names on it, or the General Contractor or sub contractors may know who the other companies are, and they don't want that information to get out yet.
None the less all this secret BS has to go