Tiny Houses

Many property owners are interested in using tiny houses or tiny homes to house themselves or to rent out. Small homes can provide much-needed cost-effective and energy-efficient housing, and can be a creative solution to the current housing crisis.

But before you buy a tiny house yourself, be sure that you ask the right questions. There is no industry standard definition of a tiny house. The term is used to describe a variety of dwelling types, and the permitting and inspection requirements differ for each type of tiny house. Here are some terms to get you started:

• Stick-built/site-constructed homes: A small home constructed entirely at the building site.
• Manufactured houses (commonly referred to as mobile homes): Homes built in a factory mounted on a non-removable steel chassis or frame.
• Factory-built houses (commonly referred to as modular homes): Factory-constructed homes that are transported to a permanent location for installation on a foundation.
• Recreation Vehicles: Travel trailers, motor homes, park model homes, truck campers, camping trailers, or any other housing on wheels.

International Residential Code (IRC) Definition

According to the 2018 International Residential Code (IRC), a tiny house is a dwelling that is 400 square feet or less in floor area excluding lofts. The 2018 IRC Appendix Q outlines some code requirements for tiny houses. In addition to IRC requirements, tiny houses permitted by Sonoma County must meet the building regulations found in the current California Building Codes and Chapter 7 of the Sonoma County Municipal Code.

Review and Approval Requirements

There are distinct review and approval requirements for the different types of tiny houses as outlined below:

• Stick-built/site-constructed houses in Sonoma County are reviewed as part of the normal building permit process at Permit Sonoma. Current regulations require tiny houses to be built on permanent foundations.
• Manufactured houses are regulated by the US Department of Housing and Urban Development (HUD) and installed on a State-approved foundation.
• Factory-built houses are regulated by the California Department of Housing and Community Development (HCD) and inspected in the factory to ensure that building codes are met. See Permit Sonoma’s policy on Factory Housing Permits (PDF 44.9 kb).
• Recreational Vehicles (RVs) are constructed to national standards including ANSI 119.5 and NFPA 1192 standards. They must be registered and licensed through the California Department of Motor Vehicles (DMV). RVs and other housing on wheels, compliant with the above regulations, are allowed for only temporary housing for homeowners during construction of a home or major addition, caregivers, or agricultural employees, according to PJR-008 Temporary Occupancy of Travel Trailers, Recreational Vehicles and Mobile Homes.

Planning Division Requirements for Use of Tiny Homes

Accessory Dwelling Units

If a tiny home on a permanent foundation is proposed to be used as an accessory dwelling unit (i.e., in addition to a primary residence), it must meet the requirements in State law. Recreational vehicles (RVs) do not qualify.

Cottage Housing Developments

Tiny homes on permanent foundations may be used as cottage housing developments in accordance with the Cottage Housing Ordinance. Recreational vehicles (RVs) do not qualify.

Agricultural Housing

Tiny homes on permanent foundations may be used for agricultural housing. Recreational vehicles (RVs) may qualify for temporary farmworker housing.

Special Occupancy Parks

Organized Camp vs. Special Occupancy Park