I recently realized something odd about myself: whenever I read about anything taking place in a house, fictional or otherwise, I always envision it taking place in a house with a floor plan based on one I’ve lived in. Which house it is seems to be random, though there is a bias towards ones I lived in when I was younger, and I do this even if the actual description of the house conflicts with the one my brain’s chosen; that is, it will sometimes add things to my mental house to fit the description, for instance replace a hallway with a staircase if the house has a staircase (I’ve only ever lived in one-storey homes) but the general layout of the rooms is never changed. Every now and then I have a “mental house” that appears original but they pretty much always turn out to be an old house in disguise. It’s a bit odd since I don’t imagine people I read about as people I know, or cars, or anything else for that matter. Are my spatial skills so bad I can’t construct a mental house on-the-fly, and instead have to borrow a “pre-fab” from my memories? 
I do this all the time, too.
Sometimes I even imagine a house I’ve seen in a movie, or on TV. Maybe it’s just lazy imagination – I dunno!
But really, unless the author gives a pretty good description, I think it only makes sense that we imagine places we’re familiar with, or that fit the tone of the book.
I’m reading a book right now called Blind Lake, and I can’t help but imagine the dwellings as one of my friend’s house. One of the descriptions the author used reminded me of his house, and now I can’t shake that impression.
I also just realized, that I imagine every protagonist to always look like some generic man (unless otherwise stated by the author). It’s always seems like the same, featureless guy. But even then, I can never really picture a face… it’s just some vague, foggy impression I have of an idealized dude. Yet, with women protagonists, I have a much easier time. Maybe because that’s what I’m attracted to, and those characteristics register far more IRL, so I just project that onto the characters?
Man, I dunno. (Almost) EVERY character in a book is a vague blur of generic features to me. Even (especially?) if the author describes them in excruciating detail. I have a lot of trouble drawing book characters.
Not quite exactly, but I have a mental “generic house” that I use that is more or less an amalgam of the typical houses that were in my neighborhood growing up.
It is always disconcerting when an author messes this up. Here I am, innocently reading along, and the book will say something like “then she went through the laundry room into the garage.” But in the house in my head, you can’t get to the garage through the laundry room, that is just nonsense! 
I always see a 2 story house, the kind with the stairway right near the front entrance, large, spread out, and somewhere there is a way to get to the basement.
I’ve never lived in that house, and I’m sure I have never visited. I have no idea where it comes from.
I do have a generic car in my head, kind of a Fisher-Price model, full size.
There was this big old house that must have at some point gotten bought by the YWCA in our town, because Mom would have meetings there. But it still had the glorious big wooden panelled staircase and library/den area of yesteryear. That’s what I picture whenever a book is set in a glorious old house. I sometimes wonder what it really looked like, since I was seeing it through kids’ eyes.
And my grandma’s living room figures largely in imaging any comfortable old timey place.
I do this all the time, especially with individual rooms. For instance, if something’s taking place in a bathroom, I envision a particular bathroom in a house I’ve lived in. But a bedroom might be from a different house. Yards too, and offices.
I do a variation of this, but it involves different places I’ve been. For example, the “ranch” (really a farm) in this one British book I like to reread upon occasion seems to take place in this one ranch (meaning one level, NOT a farm house at all) I was in and out of as a child (neighborhood house). The property is extended, but the layout of the house is the same as in RL, just bigger rooms etc. No idea why. Rarely (if ever) do I picture any action happening in the house I grew up in.
I also imagine different rooms and houses, but usually based on some personal experience. Not always, though–I can picture a place I’ve never been before and see it quite clearly. Whether it matches what the author had in mind is a whole different story…
I always imagine the Brady house.
I also used to fantasize about Alice.
I am so ashamed.