Bathroom and dryer vents running into attic

[Tim Mensch]

I'm currently in the process of buying a rental in Philadelphia.  The seller will not vent the dryer and fan vents through the roof. They currently vent a few inches from the ridge vent.   I know the reasons they should vent through the roof but was wondering if they HAD to be vented outside. I can't find the code anywhere.  Listing agent says there is no use and occupancy requirement to make the change.