Depending on the age of the house and the requirements and the time that the house was built you could check with your locality's recorder's office. I know where I live you're required to have a copy of the blue prints on file there for every house that is built.
Do you mean actual blueprints or something like a catalog of a bunch of houses w/floor plans? You can get catalogs from places like Home Depot or Menard's
A lot of times you can get floorplans to Mobile homes they seem to have larger bedrooms.
