Legal Non-Conforming Use

Given the impact of zoning and building permit regulations on property owner’s and the public’s daily lives, most people do not realize that zoning ordinances and building codes have only been around for approximately 50 years. Many parcels were created and many structures were built prior to adoption of zoning ordinances and building codes by Napa County and our five municipalities. The law provides that pre-existing lots or structures that were legal when created or built but would now be prohibited or restricted under current zoning regulations or building codes may be called “legal nonconformities.”

Establishing Status

To establish the status of legal nonconformity a property owner may need to apply for a Certificate of Legal Nonconformity from the Planning Department of the appropriate local agency. Evidence from historical sources, records of prior owners and assessor records will be needed to support the application. Once granted, a certificate of legal nonconformity allows the lot or structures to continue in use for whatever time period is set forth in the Certificate of Legal Nonconformity. Some communities allow the use to be maintained, repaired and rebuilt following destruction regardless of the extent of the destruction. The original size and location of the nonconforming structure may restrict the extent of rebuilding after a disaster or remodeling. 


To maintain a legal nonconforming status the use of the parcel or structure cannot be abandoned. Abandonment usually refers to a period of time with certain leeway for reconstruction if the use was discontinued because of a calamity or misfortune.

Value of Property

Whether or not a lot or structure is a legal nonconformity can make a substantial difference in the value of the property when offered for sale. In a recent instance a parcel was sold with two existing homes which both dated from the early 1900s. The municipality notified the new buyer that one of the homes might have to be removed as current zoning only provided for one unit on the parcel. However, once the status of the second home was clarified as a legal nonconformity using information provided from assessor records, the municipality allowed the new buyer to continue using both structures. In other instances, buyers took title to property without investigating the status of second units or garage conversions. 

If those uses had been done without permits or contrary to existing zoning at the time they were commenced, the use does not qualify as a legal nonconformity and would have to be discontinued and in some cases torn down.

As a minimum, any buyer of real property should obtain from the seller the right to see the confidential assessor records for that parcel.

Contact Information

Should you have any questions please contact Napa County Assessor-Recorder-County Clerk John Tuteur at 707.253.4459 or by emailing John Tuteur. More articles can be found on the Assessor's page.