Student or Learner
My dictionary defines a bungalow as follows:
A bungalow is a one-storeyed house.
Would it be wrong is I change it to 'one-storey house? Why should -ed be added in the definition?
I would not use storeyed. I would use one/two-storey house, though I would use Bhaisahab's suggestion too.
I would use story.
This building has one floor.
But you cannot say "one floored building". Well, you could, but you shouldn't.
EDIT: never mind. You wrote "story" not "storey". Yes, Americans say story, but floor is more common, at least in my experience.
I'd say "single-story house."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.