Re: sims 3 wont stop filling up empty houses

@okeydesuka  There are a couple different approaches to dealing with this issue.  One is to set StoryProgression to not move sims into houses.  Click on City Hall and select this:

NRaas > SP > General Options > Options: Lots > Options: Immigration/Emigration > Immigration Gauge > 0

StoryProgression does need to be active for this setting to work:

NRaas > SP > General Options > Enable Progression > True

You may also need to add NRaas Register and set Allow Immigration to False; otherwise, immigrant sims may be generated to fill role positions like staffing a bar or cash register.

Or you could go with the quick and dirty way, courtesy of igazor: remove the fridge from any empty house.  Sims won't move into a house that doesn't have a fridge.

If none of this helps, please let me know who the sims are that keep showing up.  Running MasterController Status on them (NRaas > MC > Sim > Status > Career, or try other Status categories if that comes up blank) should tell you what they're doing in town.