Where do the spiders get in?

This time of year, we usually find one or two wolf spiders in our sinks and bathtubs in the morning.  They're harmless, but ugly -- and big (the size of a silver dollar).  Mrs NoCo and I happened to discuss this yesterday, and she always thought they climbed out of the drains.  I said no, they just climb along walls and countertops and occasionally fall into a basin with slippery sides and they can't get out.

The drain system is, by definition, sealed to the outside.

But that raises the question though: where do they get in?  I assume they come indoors to get out of the colder outside.  They could slip under the garage door or the side door to the garage.  Not the front door.  Not the sliding glass door to the deck.  And once they got in the garage, there's still no path to inside the house.

If they came in via the attic, I'm not sure how they get down into the living space.  Via the bathroom fan?  Assuming they move around in the ceilings and inside the walls, where do they exit to the living spaces?  It's not like we have a lot of holes in the walls. Our furnace ducts are sealed (or they'd better be!)

The more I think about it the more puzzling it becomes.

Our spiders are smaller, but I always assumed they climbed out of the drains.

Young spiders are incredibly small. There are countless entries for them in the typical home.

Wolf spiders aren't really harmless. The venom isn't lethal, but if bitten you should definitely seek treatment. I still have a scar from a wolf spider bite that got so necrotic it took out a section of tissue about the size of a dime. It's been 12 years and you can still see the scar. Wolf spider bites are nasty and need medical treatment.