Casita

A casita — Spanish for "little house" — is a small, secondary living space on a residential lot, most often a detached structure separate from the main home. The term is widely used in the Southwest and parts of the West (Arizona, New Mexico, Texas, and California especially) and, in the housing context, generally refers to what building codes call an accessory dwelling unit. Like other regional names — granny flat, in-law unit, backyard cottage — "casita" is a colloquial label rather than a separate legal category.

What counts as a casita in everyday speech can range from a fully self-contained unit with its own kitchen and bathroom to a guest room or studio without a full kitchen. That distinction matters for permitting: if the space includes independent provisions for cooking, sleeping, and sanitation, it generally qualifies as a dwelling unit and is regulated as an ADU; a guest room without a kitchen may be treated differently. The label on a listing or in conversation doesn't determine the rules — the features and intended use do.

Because a true casita is, in regulatory terms, an ADU, it follows the same path as any accessory unit: it requires a building permit, must meet zoning rules like setbacks, and typically needs a certificate of occupancy before it can be lived in. Whether it's detached or attached follows the usual detached vs attached distinction. Because terminology and the rules behind it vary by jurisdiction and change over time, treat this as a general overview and confirm how your city classifies and regulates a casita or ADU with the local planning department.