4-0-10 Placement of Manufactured Homes on Private Property

To establish a procedure for permitting and inspecting a manufactured home or mobile home on private property. For the purpose of this policy, a manufactured home shall be considered the same as a mobile home.

The scope of this policy applies to manufactured homes intended for permanent use placed within the unincorporated county, excluding mobile home parks. Manufactured homes placed within mobile home parks fall under California State Department of Housing and Community Development (HCD) jurisdiction and are not addressed within the scope of this policy. Manufactured homes intended for temporary use are addressed under Permit Sonoma Policy 8-1-1 Temporary Occupancy of Travel Trailers, Recreational Vehicles, and Transportable Housing Units (Tiny Homes) (PDF).

Federal Housing and Urban Development (HUD) and the California Health and Safety Code Section 18551 establish regulations for the construction and placement of manufactured homes. As a general rule, federal and state regulations preempt local building standards and establish a procedure for permit issuance. Applicable laws allow local zoning regulations to limit installation options. Permit Sonoma’s responsibility consists of verifying the submitted information complies with either HUD or HCD standards as limited by our zoning regulations.

HCD oversees the manufacture of units that are sold, leased, and used within the State of California. Units manufactured outside the state of California must meet HUD standards. All manufactured homes must be permanently labeled to identify their date and location of manufacture.

HCD retains jurisdiction and is the permit authority for any alterations or repairs to the structural framing, roofing, siding, plumbing, electrical, mechanical or fire sprinkler systems within a manufactured home. Permit Sonoma has jurisdiction of the support system and is the permit authority for any site-built additions, carports, garages, cabanas, ramadas, porches, decks and stairs. Permit Sonoma has jurisdiction over utilities servicing a manufactured home as with any other residential structure.

Our zoning regulations allow manufactured homes to be used as a dwelling unit, agricultural employee housing or as a temporary construction site dwelling in accordance with Permit Sonoma Policy 8-1-1 Temporary Occupancy of Travel Trailers, Recreational Vehicles, and Transportable Housing Units (Tiny Homes) (PDF).

Health and Safety Code Section 18551, California Building Code as amended by the County of Sonoma

1. Conversion to Real Property is the process of converting a manufacture home from Personal Property (movable property) to Real Property via completion of a Building Permit application and the the required HCD forms.
2. Factory Built Housing - See Permit Sonoma Policy 4-0-9
3. Manufactured Home is defined per Section 18007 Health and Safety Code as a structure that was constructed on or after June 15, 1976, is transportable in one or more sections, is eight body feet or more in width, or 40 body feet or more in length, in the traveling mode, or, when erected on site, is 320 or more square feet, is built on a permanent chassis and designed to be used as a single-family dwelling with or without a foundation when connected to the required utilities and includes the plumbing, heating, air conditioning, and electrical systems contained therein.
4. Mobile Home is identical to Manufactured Home except constructed prior to June 15, 1976.
5. Permanent Foundation System  is considered a permanent support system consisting of concrete footings, piers or stem walls conforming to Title 25, Chapter 2, or Title 24 Part 2 of the California Code of Regulations.
6. Note: Sonoma County Zoning Code does not allow the use of Permanent Foundation System on Manufactured Homes over 10 years old per Section 26-88-090(c)2.
7. Non-Permanent Support System, commonly known as a “Set-up” is defined as a support and anchorage system designed to support vertical loads and resist wind and seismic forces per HUD or HCD standards. It is not considered a Permanent Foundation System and may be visually indiscernible from a Permanent Foundation System.

1. Permit Type Based on Foundation System

   1. The applicant shall apply for a building permit application if a manufactured unit is proposed to be installed on a permanent foundation system as real property. 
   2. If the applicant chooses to apply for a temporary placement of a manufactured home on a property, the applicant shall apply for a Temporary Permit application (TEM) and adhere to the procedure and requirements of Permit Sonoma Policy 8-1-1 Temporary Occupancy of Travel Trailers, Recreational Vehicles, and Transportable Housing Units (Tiny Homes) (PDF).

2. Application and Plan Review

   1. A complete set of plans for the proposed manufactured home and permanent foundation system shall be uploaded at the time of the Building Permit application.  The plan set shall include a Cover Sheet, Site Plan, floor plan(s) of the manufactured unit that have been approved by HCD, and adequate plans of the proposed foundation support system. The support system proposed must be approved by the California Department of Housing and Community Development (HCD) specifically approved as a “Manufactured Home Foundation System.” As an alternative, the plan may be designed, stamped, signed, and dated by a California licensed professional engineer or architect. The plans and scope of work shall also include any adjacent decks, stairs, covered porches, and/or retaining walls associated with the scope of work proposed.
      1. If the application is submitted under stamp and signature of a State licensed professional, plan check fees may apply to the foundation system and permit fees shall be calculated on the lineal footage of the exterior building perimeter.
      2. If the application is submitted with a HCD approved Permanent Foundation System, plan check fees may not be collected for the foundation system. Permit fees shall be calculated based on the lineal footage of the exterior building perimeter.
   2. The HCD approved manufacturer’s installation manual shall be uploaded to the application’s documents prior to acceptance. If the installation manual is not available, a generic installation manual authored by a private testing agency authorized by the U.S. Department of Housing and Urban Development (HUD) is acceptable. Use of the installation manual for a support system design is not allowed as a Permanent Foundation System unless specifically stamped by HCD and approved as a Permanent Foundation System, and the appropriate plans and details are included in the plan set uploaded.
   3. Residential Green Building Plan Review Fees at the reduced (50%) rate shall be applied to foundation systems submitted under stamp and signature of a state licensed professional. Residential Green Building Plan Review Fees shall not be applied to HCD approved foundation systems. Residential Green Building Inspection Fees at the reduced (50%) rate should be applied to all manufactured homes with a permanent foundation system.
   4. HCD Form 433(A) and HCD 433(B) forms must be completed by the applicant and recorded with the Sonoma County Recorder’s Office after installation before a certificate of occupancy can be issued.  (See Occupancy below.)

3. Permit Issuance for all Support Systems and Titling

   1. A site review is required for all applications, submitted without an associated geotechnical report or if the application is proposed in a mapped flood zone, per Permit Sonoma Policy 4-0-1.  Once the site review is complete, the application will be assigned to Plan Check staff.  Upon review, Plan Check staff will verify compliance with HUD or HCD standards or in the case of an engineered foundation system, complete a plan check review for those components.  The assigned plans examiner will identify required corrections to plans and/or to request additional information, if necessary. After the plan review and verification of standards is completed, the application package is digitally stamped and routed to the Customer Service Section who will complete the application processing, collect any relevant school fees if applicable, and invoice the application for issuance.
   2. A building permit may be issued after the following:
      1. All required approvals, including but not limited to the following, have been obtained and fees paid consisting of:
         1. Zoning/Planning
         2. Well & Septic or Sewer
         3. Fire
         4. Encroachment
         5. Grading/Storm Water
         6. All applicable development fees have been paid.
         7. All building permit fees have been paid.
   3. After permit issuance, the applicant may proceed with installation of the foundation or support system as approved and request all required inspections.  The building inspector is responsible for signing off all approved inspections in the digital permit record.

4. Final Inspection and Occupancy

   1. For those units being titled as Personal Property, no other paperwork is required. The building inspector may give final approval (inspection type 199) once all departmental approvals are granted and inspections are complete.
   2. For those units being titled as Real Property, the following additional steps are required:
      1. After installation of the unit and approval of all required inspections, the building inspector will approve inspection type 193. The applicant should be instructed to complete the HCD 433 (A) form and have this document signed by the responsible Building Inspector.
      2. The applicant shall record the HCD Form 433(A) at the Sonoma County Recorder’s Office.  Recordation fees shall be paid by the applicant.
      3. The applicant returns to Permit Sonoma with a conforming copy of the recorded HCD Form 433(A) and a check made payable to HCD for a transportable unit fee for each transportable section per the annual adopted fee. A Certificate of Occupancy, HCD-513C form, is completed and (1) copy is provided to the applicant.
      4. The plans examiner shall forward the following to the Department of Housing and Community Development:
         1. The recorded HCD Form 433(A) document.
         2. A copy of the Certificate of Occupancy, form HCD-513C.
         3. The check made payable to HCD for the transportable unit fee.
      5. The plans examiner will approve final inspection and upload digital copies of approved HCD 433(A) and HCD-513C forms to the building permit’s documents and approve final inspection with a 199 inspection activity in Accela.

California State Department of Housing and Community Development (HCD) sample forms:

1. Sample Form HCD 433A, Notice of Manufactured Home, Mobile Home or Commercial Modular Installation on a Foundation System
2. Sample Form HCD 433B, Notice to Assessor
3. Sample HCD 513C Certificate of Occupancy

Approved By: Tennis Wick, Director

Reviewed By: Department Manager:  ______________

Reviewed By: County Counsel:  ______________

Lead Author:  Bryan Waters, Senior Engineer