Many city and county governments describe their policies regarding blueprints online. You can find this information by searching for the name of your locale along with the words “property records” or “home records”. The site will likely have a section about blueprints or building plans.
How do I find my homes blueprints?
Visit the county clerk's office in the county where your home resides. This may be called the county recorder or land registrar in some municipalities. Once there, request copies of the blueprints on file for the property.