While all municipalities are different with regards to how far back their records go, nearly every city or county maintains some record of the blueprints used for buildings and homes in the area. Many of these documents can be obtained online, but the majority are too old to have electronic versions available.
The process for obtaining these public records varies from one location to the next. This is because some building plans include confidential or proprietary information either belonging to the owner of the property or the construction company who handled the project. In most cases, requests for physical documents must be made in writing at the government office where they are kept. Electronic records may be easier to obtain, especially if they are not for commercial or industrial buildings. The average residential building plan is one of the easier public documents to obtain, as many of these are retained in both physical and electronic forms, and only a few municipal offices require written documentation of the request. Blueprint seekers should be aware that a written request is often held on file for up to five years after any public documents are handed over. If an original copy is required, many city and county officials will not allow it to leave the building.